The glycosphingolipid composition of brain and visceral tissue from a patient with an unusual neurovisceral lipid storage disease, characterized by a lactosylceramide galactosyl hydrolase deficiency, was determined. Analyses of erythrocytes, plasma, bone marrow cells, urine sediment, and liver biopsy from the patient were compared with those of normal infantile controls. Abnormally high levels of lactosylceramide (GL-2a) were found in these samples. Subsequent studies on spleen, liver, kidney, lymph nodes, and adrenal gland confirmed this finding and clearly showed that the metabolism of hematoside (GM3) and glucosylceramide (GL-1a) was also affected. The accumulation of GL-1a and GM3 was most pronounced in spleen, but it was not of the order seen in the spleens of patients with Gaucher's disease that were studied for comparison. Since the disease was primarily neurological in nature, fresh-frozen brain was also studied. The level of GL-2a in gray matter was equal to that of galactosylceramide (GL-1b), and elevated amounts of GL-1a, asialo-GM2, GM2, and GM3 were also found; the only major abnormality in white matter was the accumulation of GL-2a and lesser amounts of the gangliosides GM3 and GM2. Chemical and enzymic evidence suggests the use of the term “lactosylceramidosis” for this disease.

Analyses have been made of glycosphingolipids from visceral organs and brain of a patient with an unusual lipid storage disorder diagnosed initially as classical Tay-Sachs disease. Levels of the lipids from fresh-frozen sections of gray and white matter, kidney, spleen, liver, and heart from this patient were compared with those of normal juvenile controls, and the fatty acid composition of accumulated glycosphingolipids was compared with reference compounds. This patient was found to have abnormally high concentrations of a globoside in liver, kidney, and spleen, asialo GM2 ganglioside in brain and liver, and GM2 ganglioside in the brain. On the basis of these findings along with the clinical manifestations of Tay-Sachs disease with visceral involvement (hepatosplenomegaly) and demonstration of total deficiency of both A and B components of β-N-acetylhexosaminidase activity, this glycosphingolipidosis is the same as two previously reported cases of GM2 gangliosidosis with globoside accumulation and total β-N-acetylhexosaminidase deficiency.

An asymptomatic, ophthalmoscopically visible proliferation affected the optic disc and nerve of two aged horses. The lesion consisted of an accumulation of foamy cells, histologically akin to fat cells, which contained an unidentified lipid-like material. The affected area and its environs were permeated by tortuous, thickened blood vessels with heavy deposits of collagen in their walls. The neuropathy is considered to be a storage disease, and although the product stored is unidentified, the lesion is similar to that of human xanthelasma. The neuropathy seems distinct from the exudative optic neuritis of horses that has been known since 1890.

Hemoglobin and the red cell have continued to set a dizzying pace as the objects of research in the two and one-half year interval since the First International Conference on Red Cell Metabolism and Function. Most exciting perhaps, is a beginning molecular attack on sickle cell disease. The story of the interaction of red cell metabolism and oxygen transport has continued to unfold, and we can now infer that patients with hypoxia usually utilize red cell metabolic adjustments to improve oxygenation. This puts the red cell squarely in the center of medical practice, since much of medicine-heart, pulmonary, and blood diseases - deals with inadequate oxygenation. On April 27th through the 29th, 1972, crystallographers, chemists, biochemists, physiologists, geneticists, and physicians from many medical disciplines met in the Towsley Center for Continuing Medical Education at the University of Michigan, Ann Arbor to present new data, to review recent developments, and to try to piece together additional features of the red cell puzzle. The meeting was dedicated to Dr. Francis John Worsley Roughton, Professor Emeritus of Colloid Science, University of Cambridge, England, in recognition of his numerous excellent contributions to the understanding of hemoglobin and red cell function. The program got off to a good start with a paper from M.F. Perutz, Nobel Laureate, on the structure of hemoglobin. Dr. Perutz also key-noted the Conference with a special lecture on heme-heme interaction. A number of fascinating papers were presented on various aspects of hemoglobin, its structure, its interaction with ligands such as oxygen, and its properties under varying conditions. Red cell metabolism was considered, in depth, from many viewpoints, including defects in uremia, interactions with serum phosphorous, male-female differences, the role of catalase, genetic selection for quantitative variation, and mechanisms of glycolytic response to altitude stress and to anemia. As with the first conference, a session was devoted to the continuing assessment of the importance of decline in red cell oxygen transport functional capacity during blood bank storage. A session was also devoted to consideration of carbonic anhydrase and carbon dioxide transport, and the interaction of this area with oxygen transport. A high point of the conference was the session on sickle cell structure and function. Excellent papers were presented on cyanate, including results of some early clinical trials which look promising. A trial with oral urea in sickle cell disease indicating possible usefulness of this approach was presented. The antisickling properties of carbamyl phosphate were also discussed. The present status of prenatal diagnosis of sickle cell disease, and the sickling phenomenon of deer erythrocytes, were other interesting topics. The discussions in the general area of sickle cell disease and the mechanisms by which antisickling agents act were quite interesting because of the diversity and expertise represented in the audience. This volume contains the Proceedings of this second conference. It includes the formal papers and much of the informal discussion after the papers. It represents a compilation of the present state of the art, and the status of current thinking, in the various areas discussed above.

Described are investigations, carried out in 1963 to 1971 in Hevea brasiliensis at the Firestone Plantation at Harbel in Liberia. Studied was the tapping panel disease, black thread, caused by the fungus Phytophthora palmivora. The emphasis of the investigations was on control of the disease with the fungicide captafol (Difolatan). Another line of investigation was yield stimulation with 2,4-D (salts and esters of 2,4-dichlorophenoxyacetic acid) and ethephon (2-chloroethyl-phosphonic acid; commercial formulation named Ethrel), to combine application of yield-stimulants above the cut with application of captafol for black thread control. A new method of yield stimulation was tested: application of ethephon to scraped portions of the vertical guide lines.General information on rubber in Liberia is given in sections 1, 2 and 3. Rubber is the most important cash crop grown in Liberia and accounted for 20 % of total exports in 1969. Liberian rubber production amounted in 1970 to 2.2 % of world production of natural rubber. Particulars on rubber cultivation at the Firestone Plantation at Harbel are given in Section 2. On this plantation about 25,000 ha of rubber are in production. There are 2 distinct seasons, a dry season from November to April and a rainy season from May to October. Production is lowest in the middle of the dry season when trees are wintering and refoliating.The economic importance of diseases in Hevea is difficult to assess as the damage depends on local conditions, which also may change with time. Moreover, very different types of damage must be compared. Within these limits it was concluded that diseases are likely to be of less economic importance in Liberia than in many other rubber producing countries. The most important diseases probably are: black thread, root rot diseases (Fomes and Armillaria) and leaf diseases (Helminthosporium and Gloeosporium). Brown bast - the result of a physiological disorder - is another very damaging disease. Pests are generally of minor importance (1).A review is given of all known diseases, pests and other causes of damage of Hevea in Liberia (3). It is remarkable that bird's eye leaf spot (caused by Helminthosporium heveae) was such an important leaf disease in young plantings of 4 to 8 years old; in the Far East, the damage is mainly confined to the nurseries. Wide-spread damage by patch canker (caused by Pythium vexans), done to the root collar, is also rather uncommon in most Hevea growing countries. Mouldy rot, a known tapping panel disease in the Far East and caused by the fungus Ceratocystis fimbriata, was never encountered in Liberia.Black thread diseaseLiterature on different aspects of this disease is reviewed, viz. on symptoms and damage (4.1.1) and on the causal agent, sources of infection, dissemination and predisposing factors (4.2.1.). In Liberia, black thread is often the most important disease in plantings of above average susceptibility. Highly susceptible Hevea clones, planted on a large scale, are BD 5 and Har 1. These clones are also highly susceptible to patch canker (4.2.3).Black thread causes rotting of the renewing bark. The recently tapped portion of the panel is subject to infection during the rainy season. The diseased bark deteriorates, the cambium is killed and, eventually the wood is exposed. In severe cases, large parts of the tapping panel are affected, rendering subsequent tapping impossible. Secondary infections may increase damage (pinhole borers; the fungi Ustulina zonata and Pythium vexans). Older trees with a severe black thread history are probably also more liable to wind damage (trunk snap); sections through stems of such trees showed irregular wood formation with necrotic parts (4.1.3.). Generally, the wounds start healing with the onset of the dry season. However, healed wounds have irregular bark, which is difficult to tap and possibly of lower yield potential. Progress of healing tissue was generally between 0.75 and 1.5 mm. per month (4.1.2. and 6.3.5.2). Healing was slowest during the driest months. Application of 2,4-D to artificially made wounds promoted healing (6.3.5.2). Black thread is most predominant in August and September at Harbel, the months with little sunshine, relatively low temperature and highest rainfall (2 and 4.2.2).It is known that infection takes place by means of sporangia or their zoospores. Severe infections built up on panels protected against rain with polyethylene sheets, thus visibly dry panels can also be infected; a higher than normal relative humidity is maintained under such aprons (4.2.2).There is a distinct positive correlation between the incidence of new and old black thread damage on the same tree (4.2.4). It is not clear whether the old wounds are a source of infection to the underlying portion of the panel, tapped during the next rainy season; disinfection of the old wounds had no effect on later disease incidence (4.2.8). At any rate, as the disease in general builds up each year on the same trees - also in clonal plantings - it might be advisable to take trees with a severe black thread history out of tapping for the entire rainy season; such a measure will also prevent spread of the disease to neighbouring trees (4.2.7). The disease is generally more predominant in low-lying areas close to swamps, probably because of the more humid microclimate (4.2.5). The tapper is probably an important factor in the spread of the disease. He spreads the disease presumably with his hands; the tapping knife is probably of lesser importance (4.2.6).A rather unusual case of black thread damage on panel marks is also reported. It was concluded that when new panels are laid during the rainy season, the drawn channels should be protected with a fungicide (4.1.5).Control of black threadVarious fungicides were tested because the product used in practice (Treseal, a petroleum jelly) gave unsatisfactory disease control in Hevea clones of above average susceptibility. In bio-assays (5.3), captafol proved to be a stronger fungicide against P.palmivora than the related compound captan, which latter chemical was of promise in CARPENTER's experiments (1954). Next, these and other fungicides were tested in field trials.Most field experiments had a randomized block or a replicated tree plot design. The trials were laid out in such a way that the damage done in the previous rainy season was of the same level in all treatments, in order to level the chances of infection. The damage was evaluated according to a scale: '0' (no damage) to '6' (maximum damage possible). The panels were exposed to natural infections; no use was made of artificial inoculation (5.2.2.2. and 5.2.2.3.).Very satisfactory disease control was obtained with 1 % captafol suspension in water, applied weekly with a brush on a 2-2.5 cm wide strip immediately above the cut (5.4 and 5.5.). Antimucin, an organic mercury compound - much used in the Far East - gave very little protection when applied weekly in 0.8-1.0 % concentration (5.5.1.). Under the described conditions the optimum concentration for captafol. was probably about 1 % (5.5.2.). In Malaya, Difolatan is recommended in 2 % concentration, to be applied after every tapping. In most experiments, 0.1 % Ortho spray sticker was added to the suspension, although it has not yet been proved that this gives better disease control. Results indicate that products with very effective sticking properties (such as high concentrations of wax emulsions) might even lower the effectiveness of captafol (5.5.3.). A suitable colouring agent for captafol suspensions in water is yellow iron oxide, added to make captafol application to the panel visible (supervision). However, some Sterox NJ (a synthetic detergent) should be added to keep the powders better in suspension. Very satisfactory results were obtained with the following mixture in experiments and commercial practice: 1.25 % Difolatan 80 WP (containing 1% captafol) + 1 % yellow iron oxide (grade YO-2087) + 0.1 Ortho sticker + 0.01 % Sterox NJ in water (5.5.4.).It should be emphasized that a homogeneous suspension must be prepared or otherwise disease control is less effective. Therefore, a slurry of the Difolatan powder should first be prepared. If too much water is added, the aggregated Difolatan particles do not separate and an unstable suspension is immediately obtained. After this stage, more water should be added whilst stirring, and then the other ingredients added. The whole procedure can be simplified and speeded up with the aid of strong electric agitators. The quantity of water added at one time to the Difolatan powder is then less critical. It is practical, however, to prepare first a concentrate of 20 times the strength applied to the trees and to dilute with water on the day the applications have to be made. The concentrate should be made up no earlier than I month in advance because of decomposition of captafol during prolonged storage (5.7.).The residue of captafol on treated panels is rather persistent; however, most of it had disappeared 5-6 months after application (disintegration, dissolution, particles dropped off, particles washed off by rain). This fungicide does not penetrate into the living tissues of the bark (5.6.). It is likely that the protective action of captafol is based on the traces of it which dissolve in the water film on wet panels (7).Side effects of captafol applications were also studied (5.5.8.). Chances are extremely remote that normal captafol applications have adverse effects on the physical properties of the rubber (5.5.8.1.). Latex yield and yield potential of treated renewing bark were also normal (5.5.8.2. and 5.5.8.3.). However, captafol treatments have a temporarily retarding effect on the activity of the cork cambium, initially reducing hard bast and cork formation; soft bast renewal is about normal from the beginning. It is to be expected that the initial differences in bark thickness between treated and untreated panels will have disappeared when the bark has fully matured and is to be tapped again at the age of 8 to 10 years (6.3.5.1.). Bark renewal can be improved when low concentrations of 2,4-D are added to the captafol mixture.Yield stimulationThis subject is introduced with a brief review of literature. Illustrations are given of 4 stimulation techniques (Fig. 15), which are:a. weekly above-cut stimulation.b. stimulation of a scraped band of bark parallel to and below the tapping cut.c. stimulation of lightly scraped portions of the vertical guide lines.d. stimulation of lightly scraped, vertical narrow strips of bark below the cut.The experiments had a replicated tree plot design and layout was based on pretreatment yield data. So, trees were allocated to treatments in such a way that the mean production level of each treament was about the same. Layout can also be based on pretreatment girth measurements as yield and girth of the stem are positively correlated in clonal plantings. However, the correlation between later yield and pretreatment yield appeared to be significantly higher than between later yield and girth (6.2.2. and 6.2.3.). For experiments of relatively short duration, taken in older plantings, pretreatment yield data are definitely to be preferred.Important yield increase was obtained with weekly above-cut application of 2,4-D in aqueous media (with and without captafol and other admixtures), although lower than with 2,4-D in the petrolatum Treseal. However, 2,4-D in Treseal is only applied during the last tapping cycle in commercial practice, because the treated bark becomes greatly proliferated. There is much less bark proliferation with 2,4-D in aqueous media. This method is fairly promising for younger plantings and for older rubber with thin bark renewal; in concentrations up to 0.25 % the thickness of the renewing bark can be increased without much bark proliferation (6.3.1. and 6.3.5.1.).With Ethrel in aqueous media (with and without captafol. and other admixtures), also applied weekly above the cut, still higher yield increase was obtained, viz. in a concentration of 1 % ethephon. Yield increase was very low in 0.25 % concentration, probably because ethephon was disintegrated (the higher the pH the faster is disintegration). Yield increase was very high in 2.5 % concentration (6.3.2.).The novel stimulation technique, i.e. application of Ethrel in palm oil on scraped portions of the vertical guide lines, showed much promise. In a concentration of 5 % ethephon, applied to 4 inches (10 cm) of each of the 2 guide lines, yield increase was about of the same level as with 1 % ethephon in water, applied to a 2-inch-wide scraped band below the cut (6.3.3.). A detailed description of this technique was given in Section 6.2. . The preliminary results indicated thefollowing:1. A portion of each of the 2 guide lines should be treated.2. It is of little importance which portion of each guide line is treated (above or below the cut). However, it is impractical to treat the front channel below the cut because the spout is positioned there.3. An effective length is 10 cm per guide line. Treatment of longer portions gave relatively low extra yield increase. It is worth trying to treat shorter portions, e.g. 5 cm per guide line.4. The same portion can be scored and treated for a second time within a few months. When a portion of 10 cm per guide line is treated then the trees can be stimulated every 2 months, provided bark consumption is at least 2.5 cm per month, the condition or the bark allows for a second treatment and continuous stimulation is wanted.5. Scraping of the guide lines is essential to obtain effective penetration of ethephon. Only the dead bark layers are removed.6. Ethrel should be applied in palm oil rather than in aqueous media (higher yield response and easier to apply). 7. The optimum concentration is presumably 5 % ethephon or higher.The conclusion was drawn that this method merits further testing since high yield response was obtained at low Ethrel consumption. Moreover, the tapping panel itself is not treated, so that the risk of undesirable side-effects on bark renewal should be lower.Results of measurements of bark thickness suggest that ethephon applications (above-cut, below-cut or on guide lines) have no or little effect on bark renewal (6.3.5.1.). However, it is still unknown whether bark renewal will continue to be normal when trees are stimulated intensively with high concentrations of ethephon for many years, as ultimate exhaustion of the tree - because of excessively high withdrawal of latex - may have adverse effects on growth. In younger plantings, girthing of the trees should be closely watched.This chapter on yield stimulation is concluded with some considerations on effectiveness and profitability of different stimulation methods with Ethrel (6.4.). The calculations showed that relatively small increases in yield already compensate for the costs of rather expensive stimulation methods under the described conditions when the normal yield level is at least 900 kg dry rubber per ha and per year. Therefore, it is probably more important to put the emphasis in stimulation trials on safe methods, which are likely to have little effect on future yields, rather than on cheaper methods (7).

Described are investigations, carried out in 1963 to 1971 in Hevea brasiliensis at the Firestone Plantation at Harbel in Liberia. Studied was the tapping panel disease, black thread, caused by the fungus Phytophthora palmivora. The emphasis of the investigations was on control of the disease with the fungicide captafol (Difolatan). Another line of investigation was yield stimulation with 2,4-D (salts and esters of 2,4-dichlorophenoxyacetic acid) and ethephon (2-chloroethyl-phosphonic acid; commercial formulation named Ethrel), to combine application of yield-stimulants above the cut with application of captafol for black thread control. A new method of yield stimulation was tested: application of ethephon to scraped portions of the vertical guide lines.General information on rubber in Liberia is given in sections 1, 2 and 3. Rubber is the most important cash crop grown in Liberia and accounted for 20 % of total exports in 1969. Liberian rubber production amounted in 1970 to 2.2 % of world production of natural rubber. Particulars on rubber cultivation at the Firestone Plantation at Harbel are given in Section 2. On this plantation about 25,000 ha of rubber are in production. There are 2 distinct seasons, a dry season from November to April and a rainy season from May to October. Production is lowest in the middle of the dry season when trees are wintering and refoliating.The economic importance of diseases in Hevea is difficult to assess as the damage depends on local conditions, which also may change with time. Moreover, very different types of damage must be compared. Within these limits it was concluded that diseases are likely to be of less economic importance in Liberia than in many other rubber producing countries. The most important diseases probably are: black thread, root rot diseases (Fomes and Armillaria) and leaf diseases (Helminthosporium and Gloeosporium). Brown bast - the result of a physiological disorder - is another very damaging disease. Pests are generally of minor importance (1).A review is given of all known diseases, pests and other causes of damage of Hevea in Liberia (3). It is remarkable that bird's eye leaf spot (caused by Helminthosporium heveae) was such an important leaf disease in young plantings of 4 to 8 years old; in the Far East, the damage is mainly confined to the nurseries. Wide-spread damage by patch canker (caused by Pythium vexans), done to the root collar, is also rather uncommon in most Hevea growing countries. Mouldy rot, a known tapping panel disease in the Far East and caused by the fungus Ceratocystis fimbriata, was never encountered in Liberia.Black thread diseaseLiterature on different aspects of this disease is reviewed, viz. on symptoms and damage (4.1.1) and on the causal agent, sources of infection, dissemination and predisposing factors (4.2.1.). In Liberia, black thread is often the most important disease in plantings of above average susceptibility. Highly susceptible Hevea clones, planted on a large scale, are BD 5 and Har 1. These clones are also highly susceptible to patch canker (4.2.3).Black thread causes rotting of the renewing bark. The recently tapped portion of the panel is subject to infection during the rainy season. The diseased bark deteriorates, the cambium is killed and, eventually the wood is exposed. In severe cases, large parts of the tapping panel are affected, rendering subsequent tapping impossible. Secondary infections may increase damage (pinhole borers; the fungi Ustulina zonata and Pythium vexans). Older trees with a severe black thread history are probably also more liable to wind damage (trunk snap); sections through stems of such trees showed irregular wood formation with necrotic parts (4.1.3.). Generally, the wounds start healing with the onset of the dry season. However, healed wounds have irregular bark, which is difficult to tap and possibly of lower yield potential. Progress of healing tissue was generally between 0.75 and 1.5 mm. per month (4.1.2. and 6.3.5.2). Healing was slowest during the driest months. Application of 2,4-D to artificially made wounds promoted healing (6.3.5.2). Black thread is most predominant in August and September at Harbel, the months with little sunshine, relatively low temperature and highest rainfall (2 and 4.2.2).It is known that infection takes place by means of sporangia or their zoospores. Severe infections built up on panels protected against rain with polyethylene sheets, thus visibly dry panels can also be infected; a higher than normal relative humidity is maintained under such aprons (4.2.2).There is a distinct positive correlation between the incidence of new and old black thread damage on the same tree (4.2.4). It is not clear whether the old wounds are a source of infection to the underlying portion of the panel, tapped during the next rainy season; disinfection of the old wounds had no effect on later disease incidence (4.2.8). At any rate, as the disease in general builds up each year on the same trees - also in clonal plantings - it might be advisable to take trees with a severe black thread history out of tapping for the entire rainy season; such a measure will also prevent spread of the disease to neighbouring trees (4.2.7). The disease is generally more predominant in low-lying areas close to swamps, probably because of the more humid microclimate (4.2.5). The tapper is probably an important factor in the spread of the disease. He spreads the disease presumably with his hands; the tapping knife is probably of lesser importance (4.2.6).A rather unusual case of black thread damage on panel marks is also reported. It was concluded that when new panels are laid during the rainy season, the drawn channels should be protected with a fungicide (4.1.5).Control of black threadVarious fungicides were tested because the product used in practice (Treseal, a petroleum jelly) gave unsatisfactory disease control in Hevea clones of above average susceptibility. In bio-assays (5.3), captafol proved to be a stronger fungicide against P.palmivora than the related compound captan, which latter chemical was of promise in CARPENTER's experiments (1954). Next, these and other fungicides were tested in field trials.Most field experiments had a randomized block or a replicated tree plot design. The trials were laid out in such a way that the damage done in the previous rainy season was of the same level in all treatments, in order to level the chances of infection. The damage was evaluated according to a scale: '0' (no damage) to '6' (maximum damage possible). The panels were exposed to natural infections; no use was made of artificial inoculation (5.2.2.2. and 5.2.2.3.).Very satisfactory disease control was obtained with 1 % captafol suspension in water, applied weekly with a brush on a 2-2.5 cm wide strip immediately above the cut (5.4 and 5.5.). Antimucin, an organic mercury compound - much used in the Far East - gave very little protection when applied weekly in 0.8-1.0 % concentration (5.5.1.). Under the described conditions the optimum concentration for captafol. was probably about 1 % (5.5.2.). In Malaya, Difolatan is recommended in 2 % concentration, to be applied after every tapping. In most experiments, 0.1 % Ortho spray sticker was added to the suspension, although it has not yet been proved that this gives better disease control. Results indicate that products with very effective sticking properties (such as high concentrations of wax emulsions) might even lower the effectiveness of captafol (5.5.3.). A suitable colouring agent for captafol suspensions in water is yellow iron oxide, added to make captafol application to the panel visible (supervision). However, some Sterox NJ (a synthetic detergent) should be added to keep the powders better in suspension. Very satisfactory results were obtained with the following mixture in experiments and commercial practice: 1.25 % Difolatan 80 WP (containing 1% captafol) + 1 % yellow iron oxide (grade YO-2087) + 0.1 Ortho sticker + 0.01 % Sterox NJ in water (5.5.4.).It should be emphasized that a homogeneous suspension must be prepared or otherwise disease control is less effective. Therefore, a slurry of the Difolatan powder should first be prepared. If too much water is added, the aggregated Difolatan particles do not separate and an unstable suspension is immediately obtained. After this stage, more water should be added whilst stirring, and then the other ingredients added. The whole procedure can be simplified and speeded up with the aid of strong electric agitators. The quantity of water added at one time to the Difolatan powder is then less critical. It is practical, however, to prepare first a concentrate of 20 times the strength applied to the trees and to dilute with water on the day the applications have to be made. The concentrate should be made up no earlier than I month in advance because of decomposition of captafol during prolonged storage (5.7.).The residue of captafol on treated panels is rather persistent; however, most of it had disappeared 5-6 months after application (disintegration, dissolution, particles dropped off, particles washed off by rain). This fungicide does not penetrate into the living tissues of the bark (5.6.). It is likely that the protective action of captafol is based on the traces of it which dissolve in the water film on wet panels (7).Side effects of captafol applications were also studied (5.5.8.). Chances are extremely remote that normal captafol applications have adverse effects on the physical properties of the rubber (5.5.8.1.). Latex yield and yield potential of treated renewing bark were also normal (5.5.8.2. and 5.5.8.3.). However, captafol treatments have a temporarily retarding effect on the activity of the cork cambium, initially reducing hard bast and cork formation; soft bast renewal is about normal from the beginning. It is to be expected that the initial differences in bark thickness between treated and untreated panels will have disappeared when the bark has fully matured and is to be tapped again at the age of 8 to 10 years (6.3.5.1.). Bark renewal can be improved when low concentrations of 2,4-D are added to the captafol mixture.Yield stimulationThis subject is introduced with a brief review of literature. Illustrations are given of 4 stimulation techniques (Fig. 15), which are:a. weekly above-cut stimulation.b. stimulation of a scraped band of bark parallel to and below the tapping cut.c. stimulation of lightly scraped portions of the vertical guide lines.d. stimulation of lightly scraped, vertical narrow strips of bark below the cut.The experiments had a replicated tree plot design and layout was based on pretreatment yield data. So, trees were allocated to treatments in such a way that the mean production level of each treament was about the same. Layout can also be based on pretreatment girth measurements as yield and girth of the stem are positively correlated in clonal plantings. However, the correlation between later yield and pretreatment yield appeared to be significantly higher than between later yield and girth (6.2.2. and 6.2.3.). For experiments of relatively short duration, taken in older plantings, pretreatment yield data are definitely to be preferred.Important yield increase was obtained with weekly above-cut application of 2,4-D in aqueous media (with and without captafol and other admixtures), although lower than with 2,4-D in the petrolatum Treseal. However, 2,4-D in Treseal is only applied during the last tapping cycle in commercial practice, because the treated bark becomes greatly proliferated. There is much less bark proliferation with 2,4-D in aqueous media. This method is fairly promising for younger plantings and for older rubber with thin bark renewal; in concentrations up to 0.25 % the thickness of the renewing bark can be increased without much bark proliferation (6.3.1. and 6.3.5.1.).With Ethrel in aqueous media (with and without captafol. and other admixtures), also applied weekly above the cut, still higher yield increase was obtained, viz. in a concentration of 1 % ethephon. Yield increase was very low in 0.25 % concentration, probably because ethephon was disintegrated (the higher the pH the faster is disintegration). Yield increase was very high in 2.5 % concentration (6.3.2.).The novel stimulation technique, i.e. application of Ethrel in palm oil on scraped portions of the vertical guide lines, showed much promise. In a concentration of 5 % ethephon, applied to 4 inches (10 cm) of each of the 2 guide lines, yield increase was about of the same level as with 1 % ethephon in water, applied to a 2-inch-wide scraped band below the cut (6.3.3.). A detailed description of this technique was given in Section 6.2. . The preliminary results indicated thefollowing:1. A portion of each of the 2 guide lines should be treated.2. It is of little importance which portion of each guide line is treated (above or below the cut). However, it is impractical to treat the front channel below the cut because the spout is positioned there.3. An effective length is 10 cm per guide line. Treatment of longer portions gave relatively low extra yield increase. It is worth trying to treat shorter portions, e.g. 5 cm per guide line.4. The same portion can be scored and treated for a second time within a few months. When a portion of 10 cm per guide line is treated then the trees can be stimulated every 2 months, provided bark consumption is at least 2.5 cm per month, the condition or the bark allows for a second treatment and continuous stimulation is wanted.5. Scraping of the guide lines is essential to obtain effective penetration of ethephon. Only the dead bark layers are removed.6. Ethrel should be applied in palm oil rather than in aqueous media (higher yield response and easier to apply). 7. The optimum concentration is presumably 5 % ethephon or higher.The conclusion was drawn that this method merits further testing since high yield response was obtained at low Ethrel consumption. Moreover, the tapping panel itself is not treated, so that the risk of undesirable side-effects on bark renewal should be lower.Results of measurements of bark thickness suggest that ethephon applications (above-cut, below-cut or on guide lines) have no or little effect on bark renewal (6.3.5.1.). However, it is still unknown whether bark renewal will continue to be normal when trees are stimulated intensively with high concentrations of ethephon for many years, as ultimate exhaustion of the tree - because of excessively high withdrawal of latex - may have adverse effects on growth. In younger plantings, girthing of the trees should be closely watched.This chapter on yield stimulation is concluded with some considerations on effectiveness and profitability of different stimulation methods with Ethrel (6.4.). The calculations showed that relatively small increases in yield already compensate for the costs of rather expensive stimulation methods under the described conditions when the normal yield level is at least 900 kg dry rubber per ha and per year. Therefore, it is probably more important to put the emphasis in stimulation trials on safe methods, which are likely to have little effect on future yields, rather than on cheaper methods (7).

1. The history of the chickpea or gram, Cicer arietinum L., has been described from Homer's time and the earliest finds, 5450 B.C. in Hacilar, Turkey, up to the present day. The crop was first domesticated in Asia Minor and was introduced in India either from Central Asia or Asia Minor, the two main centres of origin. Some forms were even introduced rather recently. Ethiopia is a secondary centre of domestication; connections with Egypt or Asia remain speculative. Several pieces of evidence oppose the opinion of DE CANDOLLE (1882) that the ancient Egyptians and Jews had only known the chickpea for two millenia.Medical uses, no longer widely practised, are discussed. The spread to the present areas of cultivation is described and mapped.2. The genus Cicer L. has been revised. Popov (1929) accepted 22 species, now 39 species (8 annual, 31 perennial) are known. One species is described for the first time: C. multijugum from Afghanistan. A key to the species is prepared. The species, arranged alphabetically, are described and accompanied by detailed illustrations. The synonymy and typifications are given, as well as notes on geography, ecology and morphology. The geographical distribution of each species of the genus, occurring in Central Asia, Asia Minor and the Medi terranean, is presented in maps. It is stressed that the variability and geography of many species is not known sufficiently. The poor availability of fresh material of the wild species is a handicap to research.The relation to the other genera in Vicieae is discussed. Cicer occupies a somewhat peculiar place with its glandular hairs, inflated fruits and seed shape. The infraspecific classification in the cultivated species is reviewed; an informal classification is presented on base of the work of POPOVA (1937) without rejecting the older varieties distinguished by JAUBERT and SPACH, and ALEFELD.3. The importance of the chickpea as the third pulse crop in the world after beans and peas is presented in a map, graphs and tables. The crop ranks l5th among all crops in area occupied yearly. Yields, at present an average of about 700 kg per ha, are highest in Egypt (1670 kg) and Turkey (1220 kg). About 83 of the world production is in the Indian subcontinent.The weather is the main reason for fluctuation in area. The partial recession in area, due to the expanding new cereal cultivars, will be met by higher yields per unit area and aided by higher prices.4. Some anatomical particulars, e.g. the glandular hairs, are shortly reviewed.5. The chickpea is generally cultivated in a traditional way. The resistance to drought (deep roots) and ability to grow in poor soils has not increased the care of the crop. However, with good soil preparation, proper sowing on rows, cultivation and fertilization the crop can yield reasonably. The sowing date is very important. Sowing early in the growth season is to be preferred, except in case of wilt disease. Plant density, sowing depth and sowing seed are discussed. Irrigations, needed in some countries, should be practised with care so as not to induce soil anaeroby.Often the chickpea is grown mixed with wheat or mustard, against crop failures and for utilization of different soil layers. In rotation the chickpea is a well esteemed crop. It has maintained soil fertility at a certain level for centuries in the densely populated areas of India. The plants are harvested mainly by hand. Threshing machines need good adjustment to prevent breakage of seeds. Storage is an important problem, since much loss may occur.6. Ecological trials were carried out on light, daylength, temperature and relative humidity. The photosynthesis rate varied from 250-500 μg CO 2 -uptake per cm 2and per h at about 26°C, but at 18°C, the rate was not much less. Leaves of two-weeks old are the most effective in photosynthesis and may use twice as much CO 2 as the four-week old leaves. Estimated calculated production appeared to be 12-14 tons of total dry matter, or about 5-7 tons of grains, similar to the highest yield ever obtained on a small plot.The chickpea is a quantitative LD plant. Under 16-h days the flowering was advanced by e.g. 20-35 days, if compared with 9-h days. Short days did not prevent flowering. Dry matter yield was improved in LD. The influence of the photoperiodic effect alone of the daylengths following different sowing dates on flowering and yield is small. Increasing photoperiods appeared to be more favourable than decreasing ones.The optimum temperature for early vegetative growth ranges from 21-29°C (night and day) to 24-32°C for different cultivars. Over the entire growth period the optimum temperature is somewhat lower, 18-26°C and 21-29°C, which is also optimum for flowering.The relative humidity was found to have little influence on fruit-setting. A decrease in light intensity of 25 % of the available amount during May and June, however, was found to decrease the number of pods by 25-50%.Data on soils and nutrients are summarized. As yet the chickpea does not respond to dressings of more than 10 kg N and 30 kg P 2 O 5 per ha. Moderately heavy soils are preferred, but both heavy and light soils are used in some areas.Growth substances usually have a negative influence on the growth of chickpeas. Scarcity of practical trials prohibits any recommendation.Topping appears to be an old practice to stimulate branching. Regeneration, however, takes a long time and is only sufficient under optimum conditions and if applied at an early stage.7. Breeding has not yet improved yields over large areas. A review on cytogenetics is given. Some new reports on the somatic number of chromosomes of some wild species are added. As crossing technique is a delicate operation, hybridization on a large scale is at present not possible, but pollination at an early stage without emasculation may be a solution. The introduction of new cultivars has not been very successful because they have not shown large differ ences with local cultivars.8. The most important insect pests of the chickpea are the podborer and the pulse beetles, which are described in some detail. Geographical distribution and way of control is given. All reported pests are mentioned. Nematode attacks seem to be underestimated at present. Rats may cause important damage in stores.9. The diseases of the chickpea, their occurrence, possible way of control are described. Most damage is done by wilt, caused by both a soil fungus and by physiological drought, and blight. Several other diseases such as rust and foot rots are not yet serious over large areas. As for pests, chemical control is often uneconomic.10. The chickpea is mainly used as human food, whether fresh, boiled, or roasted in many preparations. As a part of balanced foods it can form an important supplement to the protein nutrition of children. The proteins of chickpea constitute an important part of the protein intake in India. The chemical composition of the seeds (e.g. up to nearly 30% of protein) is given, as well as the amounts of essential amino acids.Except sometimes for methionine and for tryptophan the chickpea appears to be an excellent source of amino acids.

1. The history of the chickpea or gram, Cicer arietinum L., has been described from Homer's time and the earliest finds, 5450 B.C. in Hacilar, Turkey, up to the present day. The crop was first domesticated in Asia Minor and was introduced in India either from Central Asia or Asia Minor, the two main centres of origin. Some forms were even introduced rather recently. Ethiopia is a secondary centre of domestication; connections with Egypt or Asia remain speculative. Several pieces of evidence oppose the opinion of DE CANDOLLE (1882) that the ancient Egyptians and Jews had only known the chickpea for two millenia.Medical uses, no longer widely practised, are discussed. The spread to the present areas of cultivation is described and mapped.2. The genus Cicer L. has been revised. Popov (1929) accepted 22 species, now 39 species (8 annual, 31 perennial) are known. One species is described for the first time: C. multijugum from Afghanistan. A key to the species is prepared. The species, arranged alphabetically, are described and accompanied by detailed illustrations. The synonymy and typifications are given, as well as notes on geography, ecology and morphology. The geographical distribution of each species of the genus, occurring in Central Asia, Asia Minor and the Medi terranean, is presented in maps. It is stressed that the variability and geography of many species is not known sufficiently. The poor availability of fresh material of the wild species is a handicap to research.The relation to the other genera in Vicieae is discussed. Cicer occupies a somewhat peculiar place with its glandular hairs, inflated fruits and seed shape. The infraspecific classification in the cultivated species is reviewed; an informal classification is presented on base of the work of POPOVA (1937) without rejecting the older varieties distinguished by JAUBERT and SPACH, and ALEFELD.3. The importance of the chickpea as the third pulse crop in the world after beans and peas is presented in a map, graphs and tables. The crop ranks l5th among all crops in area occupied yearly. Yields, at present an average of about 700 kg per ha, are highest in Egypt (1670 kg) and Turkey (1220 kg). About 83 of the world production is in the Indian subcontinent.The weather is the main reason for fluctuation in area. The partial recession in area, due to the expanding new cereal cultivars, will be met by higher yields per unit area and aided by higher prices.4. Some anatomical particulars, e.g. the glandular hairs, are shortly reviewed.5. The chickpea is generally cultivated in a traditional way. The resistance to drought (deep roots) and ability to grow in poor soils has not increased the care of the crop. However, with good soil preparation, proper sowing on rows, cultivation and fertilization the crop can yield reasonably. The sowing date is very important. Sowing early in the growth season is to be preferred, except in case of wilt disease. Plant density, sowing depth and sowing seed are discussed. Irrigations, needed in some countries, should be practised with care so as not to induce soil anaeroby.Often the chickpea is grown mixed with wheat or mustard, against crop failures and for utilization of different soil layers. In rotation the chickpea is a well esteemed crop. It has maintained soil fertility at a certain level for centuries in the densely populated areas of India. The plants are harvested mainly by hand. Threshing machines need good adjustment to prevent breakage of seeds. Storage is an important problem, since much loss may occur.6. Ecological trials were carried out on light, daylength, temperature and relative humidity. The photosynthesis rate varied from 250-500 μg CO 2 -uptake per cm 2and per h at about 26°C, but at 18°C, the rate was not much less. Leaves of two-weeks old are the most effective in photosynthesis and may use twice as much CO 2 as the four-week old leaves. Estimated calculated production appeared to be 12-14 tons of total dry matter, or about 5-7 tons of grains, similar to the highest yield ever obtained on a small plot.The chickpea is a quantitative LD plant. Under 16-h days the flowering was advanced by e.g. 20-35 days, if compared with 9-h days. Short days did not prevent flowering. Dry matter yield was improved in LD. The influence of the photoperiodic effect alone of the daylengths following different sowing dates on flowering and yield is small. Increasing photoperiods appeared to be more favourable than decreasing ones.The optimum temperature for early vegetative growth ranges from 21-29°C (night and day) to 24-32°C for different cultivars. Over the entire growth period the optimum temperature is somewhat lower, 18-26°C and 21-29°C, which is also optimum for flowering.The relative humidity was found to have little influence on fruit-setting. A decrease in light intensity of 25 % of the available amount during May and June, however, was found to decrease the number of pods by 25-50%.Data on soils and nutrients are summarized. As yet the chickpea does not respond to dressings of more than 10 kg N and 30 kg P 2 O 5 per ha. Moderately heavy soils are preferred, but both heavy and light soils are used in some areas.Growth substances usually have a negative influence on the growth of chickpeas. Scarcity of practical trials prohibits any recommendation.Topping appears to be an old practice to stimulate branching. Regeneration, however, takes a long time and is only sufficient under optimum conditions and if applied at an early stage.7. Breeding has not yet improved yields over large areas. A review on cytogenetics is given. Some new reports on the somatic number of chromosomes of some wild species are added. As crossing technique is a delicate operation, hybridization on a large scale is at present not possible, but pollination at an early stage without emasculation may be a solution. The introduction of new cultivars has not been very successful because they have not shown large differ ences with local cultivars.8. The most important insect pests of the chickpea are the podborer and the pulse beetles, which are described in some detail. Geographical distribution and way of control is given. All reported pests are mentioned. Nematode attacks seem to be underestimated at present. Rats may cause important damage in stores.9. The diseases of the chickpea, their occurrence, possible way of control are described. Most damage is done by wilt, caused by both a soil fungus and by physiological drought, and blight. Several other diseases such as rust and foot rots are not yet serious over large areas. As for pests, chemical control is often uneconomic.10. The chickpea is mainly used as human food, whether fresh, boiled, or roasted in many preparations. As a part of balanced foods it can form an important supplement to the protein nutrition of children. The proteins of chickpea constitute an important part of the protein intake in India. The chemical composition of the seeds (e.g. up to nearly 30% of protein) is given, as well as the amounts of essential amino acids.Except sometimes for methionine and for tryptophan the chickpea appears to be an excellent source of amino acids.