1) The embryo transplantation was carried out with immature grains of wheat and barley. After the operated seeds ripened, the transplanted embryos, were excised again, and examinations were made on the differentiation of several Organs : leaf, epiblast, ventral scale, radicle, coleorhyza, scutellum, axillary bud of coleoptile and length of epithelial cell. 2) In many transplanted embryos the differentiation of third foliage leaf was observed, which was equally ascertained in mature embryos of intact wheat seeds (Fig. 1). Differentiation and growth of the other organs proceeded similarly to those of embryos of intact seeds (Table 1), as in the case of leaves. High positive correlation was found between the number of leaf and the length of embryo (Fig. 2). 3) From these facts, it is presumable that the increase of embryo size is accompanied by the progress of differentiation of the organs of embryo, and that even after transplantation the embryonal growth proceeds further without developing into seedling. Therefore, it may be possible that transplanted embryos are provided with nutritional substances by the host endosperm. These results seem to have a great significance for the consideration of the influences of endosperm upon the transplanted embryo.

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The flower- promoting activity of each fraction of rye diffusate was assayed to concentrate the study of flowering substances, adopting (tiny) seeds of annual Meadow grass, Poa annua as subjects. As far as the flowering of Poa annua was concerned, the mixture of the fractions expedited flowering best. It is interesting to notice in Fig. 1 that the flowering curve of Poa annua treated with the mixture seems to be a combination of two curves of those treated with native auxin and a nucleotide-like substance. To chase this unknown nucleotide-like substance, paper chromatography and paper electrophoresis were carried out in this experiment. According to the Rf values and electric migrations of rye diffusate, adenosine triphosphate, adenosine monophosphate, uridylic acid and fructose-6-phosphate, it is considered that the effective substance may be the one which has energy-rich phosphates like uridine diphosphate or uridine triphosphate. If one of those substances truly controls the flowering of winter crops, such as wheat or rye, devernalization caused by warm temperature may be related with the heat-labile property of the substance. It would be too early to say that the flowering hormone is a complex of a native auxin and UDP (or UTP)-like nucleotide. However, if the flowering hormone were not simple in composition, these effective substances investigated in this experiment may be the core of "Florigen".

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The effect of plant density on the growth of barley planted by "the nest-sowing method" was investigated. Total plant weight per nest or per unit land area, ear yield and seed yield per unit area, total leaf area per unit land area and the ratio of the weight of the photosynthetic system to the non-photosynthetic system showed a tendency to be nearly equal irrespective of density. Individual plant weight, number of tillers per plant and the net assimilation rate decreased with increasing plant density.

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