There are many papers devoted to the inheritance of the egg-colour of silkworms by K. Toyama (1913), Y. Tanaka (1919, 1924, 1935), H. Uda (1923, 1924, 1932), E. Kawaguchi (1938 a, b), Y. Nakano (1931) and K. Suzuki (1936). In these reports we find two types of egg-colour, one being transmitted ordinarily and the other maternally. In my previous paper, I wrote on a maternal white-egg breed (w₁) which seems to be analogous to w of Kawaguchi (1938 b) and wPR of Uda (1932). Fortunately I have had another white-egg breed (w₂) which acts ordinarily. By crossing these two white breeds, I have come to the following conclusion.
1. The first white-egg breed may be represented as w₁ W₂PR and the second white breed as W₁w₂PR, where P and R are normal genes for p (pink eye) and r (red eye) respectively. W₁ is assumed to be related to the production of hormonelike substance and its function exclusively takes place at the larval stage but not in the embryonic stage, hence maternal inheritance, while W₂ produces immediately after fertilization the chromogen which gives rise to the normal egg-colour in the presence of the said hormone, hence ordinary inheritance. I support Kawaguchi's idea that the development of the egg-colour is a result of interaction of the hormone and the chromogen, I cannot, however, agree with him respecting to his conception of the pleiotropic function of these genes.
2. There is a linkage relation between w₁ and w₂, the crossing over value being calculated at 3.36% in the male, and O in the female.

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The present studies were carried out in order to obtain the most suitable germination medium for pollen grain of the sugar cane. Non-alkaline glasswares and redistilled water were used. The pH-value of the stigmatic cell sap of 2725 POJ and Em29, a variety bred in the writers laboratory, was about 5.8-6.0 in the maturity and 5.6 in the early stage. The incipient plasmolytic concentration of the stigmatic cell of the writers EE25, EE31 and 2725 POJ was 6/10mol (Table 1).
A cut panicle attached with a long stem was put in a bottle with service water and brought from the field in the glass house on the eve of the experiment. One hour after the glass house began to be exposed to the direct sunshine in the morning the pollen grains were gathered on lacquered paper, and these were used for the germination experiment.
By addition of boric acid (5×10^-5%) in the artificial culture media, the pollen germination was accelerated from 36 to 43 and its bursting decreased from 31 to 24 in percentage (Table 2 and Fig. 1). The artificial culture media, in which 6/10-7/10mol sucrose and 0, 5% agar were used, gave the highest percentage of the germination and the lowest of the bursting of the pollen grain, (Table 3, 4 and Fig. 2, 3). This concentration of sugar corresponds nearly to the osmotic value of the stigmatic cell. In a lower concentration of agar (0, 2%) or without it the pollen tubes grew often in an abnormal form (Fig. 4).
With regard to hydrogen-ion concentration of the artificial culture media, the pH-values 5.2-6.4 were favorable for the pollen germination (Table 6, 7 and 8, Fig. 5) and this range of the pH-value was wider than that of the stigmatic cell. The percentage of germination and bursting of the pollen grain increased in proportion to hydrogen-ion concentration, but an inverse relation was recognized between it and the growth of pollen-tube (Table 9). Therefore the optimum pH-value for the pollen germination seems to be about 5.6, which value is a little lower than that of the stigmatic cell.
While the best result of the artificial pollen germination in the sugar cane, which has been hitherto attained by some authors, does not exceed 61 per cent, the writers experiments showed a more satisfactory result (80%!), if sucrose, boric acid, agar and hydrogen-ion were used in proper concentration and a careful treatment was practiced.
From the results of the experiments, the writers want to recommend the following media, named 2BSA and 3BSA in their laboratory, as very available for the artificial pollen germination of the sugar cane:

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1. Abnormalities in pollen development under natural conditions were statistically investigated in five species of Crinum, C. asiaticum var. japonicum, C. latifolium, C. gigas, C. Moorei and C. sp. (Powelli?, pink-flowered), because of the necessities, 1, for the analysis of the experimental disturbances and climatic influences upon the pollen development, 2, for the cytological analysis of the hybridity.
2. In the genetically homologous species, dwarf, giant and sometimes twin pollen grains are formed in very low percentages (see the first table).
3. Examination of pollen tetrad formation showed that most of the dwarf grains were derived from both pentads and hexads, and the giant were from monads.
The mode of polyad formation in several cases suggests that those abnormalities of low frequencies in the genetically homologous individuals may be ascribed to an accidental failure of balance among the physical and chemical conditions in a few pollen mother cells, which has been caused by interactions of those conditions in the course of meiosis, rather than to the presence of slightly heterotypic nature in chromosomes of those individuals.
4. In C. asiaticum var. japonicum and C. latifolium, the abnormal grains appeared in a close proximity of their frequencies in one case, as seen in the following table:
This fact seems to support the hypothesis advanced above (3).
5. In the species which is expected to be of hybrid origin, abnormal pollen grains appear in very high frequencies, and viable and normal grains in very low (see the following table):
In addition to it, there are certain extreme abnormalities among them which could not be found in the homologous individuals, such as ultra-giant pollen grains, giant twin grains, 3-nucleate and 4-nucleate grains. Though these abnormalities can not be expected as induced by only the failure of the pairing of the chromosomes in the first meiotic division, most of the abnormal dwarf grains may be apparently expected as induced by it. So, it may be said that the abnormalities in the pollen development in a hybrid species must be discussed from more than one point of view.

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1. The rice caryopsis developed in its natural condition assumes a characteristic size and form, filling up the inside of fertile lemma and palea, which hold tightly together. If the lemma and palea are partly cut off soon after anthesis, the caryopsis takes a peculiar form, increasing its length with the decrease of the breadth. The size and form of the caryopsis developed under such conditions is demonstrated to be still characteristic for each variety.

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[in Japanese]

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