1. Sorghum seeds were germinable when their moisture content was between 50 and 60%. Soybean seeds with a moisture content of 66.9% were germinable. 2. Freshly harvested, immature seeds of sorghum were dormant. Dormancy was overcome by curing, by prechilling, and by continuing the test at 20 degrees to 30 degrees C until all viable seeds had germinated. Immature seeds of Peking soybeans from one collection were dormant and required 41 days for all of the viable seed to germinate at 30 degrees C. 3. The viability of immature sorghum seed was affected by the method of curing the seeds. Seed allowed to cure by hanging the panicles in the laboratory germinated better than that which was threshed and cured in cloth sacks. 4. Mature sorghum seed with a moisture content of 15% or less was unaffected in viability by exposure to any temperature between 33 degrees and -20 degrees F. 5. Immature seed of sorghum and soybeans was reduced in viability by exposure to low temperatures. The reduction in vitality at a certain moisture content increased as the temperature decreased. As the moisture content decreased the reduction in viability from exposure to any certain temperature decreased also. 6. Sorghum seed in small lots with a moisture content of 16 to 19% was not seriously injured by exposure for 10 hours to a temperature of -20 degrees F. Exposure for 10 hours at -20 degrees F caused serious injury when the moisture content of the seed was 22% or more. 7. Soybean seed in small lots with a moisture content of 30 to 32% or less was not reduced in viability by freezing for 10 hours at -20 degrees F. At 20 degrees F no injury occurred to seed of most varieties with a moisture content of 50 to 60%. Soybean seed may contain a much higher percentage of moisture than sorghum seed without being injured by exposure to freezing temperatures. 8. When immature sorghum seed is harvested for seed purposes high viability may be maintained by curing the seed in the panicles.

The parenchyma sheath cells enclosing the vascular bundles of the corn leaf contain specialized plastids, green in color, concerned with the elaboration of starch. The starch grains are formed in definite vacuole-like regions in the plastid. A plastid may have as many as 40 starch grains. Starch is deposited in these plastids only when the rate of movement of sugar from the mesophyll cells into the bundle sheath cells is greater than the rate with which sugar passes from the sheath cells into the vascular elements. The bundle sheath plastids deposit starch increasingly during the day. At night this starch is hydrolyzed to soluble carbohydrates and translocated so that the plastids are free of starch by morning. No starch was found in the mesophyll plastids at any time during the day or night. The bundle sheath plastids of sorghum are similar in function to those of maize ; this specialization of the bundle sheath plastids may be typical of the subfamily Panicoideae. The parenchyma sheath plastids of wheat, oats, and barley, all members of the subfamily Pooideae, are different in size and function from those of maize and sorghum. | As células do invólucro parenquimatoso que envolve os feixes vasculares da fôlha do milho encerram plastídios especializados, de côr verde e relacionados com a elaboração do amido. Os grãos de amido são formados no plastídio, em regiões definidas e semelhantes a vacúolos. Um plastídio pode apresentar até 40 grãos de amido. O amido é depositado nestes plastídios apenas quando a velocidade da transferência do açúcar das células do mesófilo para o interior das células do invólucro do feixe vascular é maior do que a velocidade com a qual o açúcar passa das células do invólucro para os elementos vasculares. Os plastídios do invólucro do feixe vascular depositam amido em quantidades crescentes durante o dia. À noite, êsse amido é hidrolizado em carbohidratos solúveis e translocado, de modo que os plastídios ficam livres de amido pela manhã. Não encontramos nenhum amido nos plastídios do mesófilo nem de dia nem de noite. Os plastídios do invólucro do feixe vascular do sorgo são semelhantes em função aos do milho ; esta especialização dos plastídios do invólucro do feixe vascular pode ser típica da sub-família Panicoidex. Os plastídios do invólucro parenquimatoso do trigo, da aveia e do centeio, todos membros da sub-família Pooidex, são diferentes no tamanho e na função, comparados com os plastídios do milho e os do sorgo.