1. The variability of the results obtained by the use of the glass and quinhydrone electrodes for determining the pH of some Iowa soils was studied, and the nature and magnitude of the "QH error" and the "QH electrode error" were determined by means of the glass electrode. The potentials of the glass and quinhydrone electrodes were checked in a potassium acid phthalate buffer solution before and after the electrodes were suspended in a soil suspension for 20 minutes. 2. The variability in the pH of 25 samples of different soils, when determined by either the glass or the quinhydrone electrode, was comparatively small and presumably of little practical consequence. 3. The addition of quinhydrone to the soil suspension increased the pH of each soil slightly when determined by the glass or quinhydrone electrodes. This change in pH resulting from the addition of quinhydrone to the soil is referred to as the "QH error". This error was scarcely large enough to make the quinhydrone electrode method unreliable for determining the pH of the soils studied. 4. The glass and quinhydrone electrodes gave similar results when employed to determine the pH of soil suspensions containing quinhydrone. The "H electrode error", therefore, is of little or no consequence in the soils studied. 5. The potentials of the glass and quinhydrone electrodes change somewhat during the process of pH determinations. It is desirable, therefore, to check these electrodes against a known buffer solution at frequent intervals.

It was found that the free ferric oxide (hydrated and unhydrated) in soil colloids may be easily separated and determined if the suspension of the colloid is first treated for about 1/2 hour with H2S. The H2S quickly changes the free ferric oxide by surface action to iron sulfides which are easily soluble in dilute acid and may thus be extracted and determined. Combined or silicate iron is unaffected in the limited time required as are also other constituents and the base exchange capacity. It was found that the amount of free ferric oxide in a lateritic soil colloid was high; in colloids from several Wisconsin soils it was less than the combined or silicate iron; and in one soil colloid and two bentonite colloids it was absent, while the combined iron oxide ranged from 4.8 to 6.3%. Free colloidal iron oxide may be removed directly from a soil without previous separation of the colloid as a whole. This is useful in mechanical analysis including specific gravity separations, petrographic work, and phosphate fixation studies.

1. A. method for the micro-determination of cystine in biological or plant material has been described. The dried material is hydrolysed with 40 per cent. sulphuric acid the cystine precipitated by cuprous chloride as the cysteine cuprous mercaptide. The cysteine content of this is determined by the modified Sullivan method. 2. The interfering colouring matter is automatically eliminated. 3. The method is quick and comparatively easy.

The absorption of methylene blue from buffered solutions is proposed as an index to wool deterioration, since it can be measured quantitatively by a simple titrimetric procedure. Exyerimental results are given for material damaged progressively under controlled conditions of laundering, and for fabrics containing wools of different grades and different dyeings. A linear relationship was found to exist between absorption and tensile strength. The reworked wool that was tested absorbed nearly four times as much methylene blue as the new serge used in the experiments. Optimum test conditions were determined and are discussed critically.

Experiments were conducted in a study of phosphorus assimilation by Aspergillus niger and Cunninghamella sp. to determine the relationship of the weight of mycelium to the concentration of phosphorus in the medium. It was found that the weight of Aspergillus niger mycelium in Niklas medium to which soil was added was roughly proportional to the concentration of phosphorus in the medium over the range from 0 to about 60 p.p.m. of phosphorus. It was concluded that the weight of Aspergillus niger mycelium in the Niklas medium to which soil has been added may be used to indicate roughly the amount of phosphorus available to Aspergillus niger if the technic employed is carefully standardized. Whether or not the phosphorus available to Aspergillus niger represents the amount of phosphorus available to crop plants was not determined.

Many spectrophotometers utilize polarizing prisms and determine the reflection factor of the sample by plane polarized light. In general, the reflection factor of the sample is independent of the azimuth of the plane of polarization but there are some materials, notably textiles, for which the reflection factor depends upon the azimuth. It can be shown mathematically that, if the reflection factor is determined for two azimuths at right angles to one another, the arithmetic average of the two values is the reflection factor for ordinary, or unpolarized light. This is true regardless of the azimuths selected. Experimental data are presented which indicate the applicability of this principle to the measurement of the color of textile fabrics.

A search was made to find factors that could be used in the laboratory to predict the relative winter hardiness of alfalfas. The results showed that the relative degree of injury of alfalfa roots by low temperature was indicated by electrical conductivity and in this manner the relative winter hardiness of different lots of alfalfas was determined. No direct relationship was found to exist between winter hardiness and heat of wetting, swelling, moisture equivalent, freezing point, chemical composition, respiration, and amount and rate of loss of moisture in roots of hardy and non-hardy alfalfas. Heredity is the most plausible explanation of the phenomenon of winter hardiness. For the time being it is necessary to adhere to field tests aided by electrical conductivity tests for determining the relative winter hardiness of different lots of alfalfas.

1. Increase in size of plat was accompanied by reduction in experimental error, but larger plats were lower in efficiency than the smaller plats. This indicated that increase in number of replications was much more efficient than increasing the size of plat. 2. The shape of the plat was determined by the direction of soil variation. The increase in size of plat in the direction of least association was most efficient. 3. Because of high seasonal variation no definite number of replications could be recommended. Each of the three methods of replication, viz., systematic arrangement, randomized blocks, and Latin squares, were studied and differences between hypothetical varieties compared with calculated standard errors. By means of X2 for goodness of fit each gave good agreement with mathematical expectation.

1 The digging movements of the freshly emerged flies have been described and analysed. Direction of digging is determined by light, but not by gravity. 2 The process of the inflation of the fly with air and the expansion of the wings has been described and analysed. During digging these reactions are inhibited and postponed. Air‐pumping occurs apparently independently from external and internal stimuli; it starts automatically a certain time after emergence and stops automatically after a certain period. 3 It has been experimentally proved that the first filling of the air‐sacs is due to negative pressure in the body arising from the diffusion of air out of the gut (in accordance with a hypothesis of Evans). 4 Colouring and hardening of the skin are inhibited and postponed during prolonged digging.