In the previous paper (SAKAI, 193^-a) the writer has reported that cytokinesis is entirely inhibited in rice by exposing the pollen mother cells to low temperature below 15°C. The writer's further investigations revealed that the same phenomenon as above mentioned has also taken place in embryosac mother cells. Following to the absence of the cell-wall formation during the macrosporogenesis, micropylar and chalazal cells fail to differentiate, the multinucleate macrospore being formed. Then it degenerates and becornes impossible to develop into the functional embryosac cf. Figs. 1-8). Frequencies of appearance of such abnonrmal macrospores which were calculated in the experiment of 1937 are given in Table 1. Diurnal periodicity of cytokinesis in micro-and macrosporogenesis was investigated (Tables 2 add 3). Occurrence of cytokinesis is 0.46 by day (8 AM to 5 PM) and O.54 by night (8 PM to 5 AM) in the next morning) in pollen mother cells and 0.54: 0.46 in the case of embryosack mother cells. According to the writer's experiment (SAKAI 1937b), it was evident that the formation of the abortive pollen grains and the decrease of fertility occur in plants when they are exposed to such a Iow temperature as above mentioned, at the stage of meiosis of the pollen mother cell. The facts presented above seem to give a possible interpretation for the occurrence of the decrease in fertility of rice in Hokkaido where the harmful low temperature attack on rice-plants not infrequently during the season of its culture, accompanying their reduction of yields.

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The author investigated the development of root system and its seasonal change in severa1 varieties of tea plant. The root system were studied by Weaver's trench method (a direct mcthod). The soil of the tea garden used was alluvial clayey loam, the top soil being of redbrown color and 105cm. in depth, and the subsoil containing a number of large gravels. The surface soil, in which most roots distribute, was about 30cm. deep. The seedling plants of five years old have usually much deeper and more vigorous root systems compared with plants of the same age propagated by layering. But as the plants grow older the roots are inclined to seem to develop more and more in adaptation to the soil conditions, and the difference in root system between the seedage plants and the clonal plants becomes smaller. In plants of twelve years old, however, the seedling plants have still deeper and wider root system than the cutting plants. The form o the root systm varied according to the varieties. Among the tree o twelve years old, the roots penetrated deeply into the subsoil in some varieties, while in the others it did not reached the subsoil. The form of the root system, also, was found closely related with the top form of the plant. The top of erect form had deep root system, while the plant o= dwarf form showed shallower root system. The plant of round form have intermediate root system. The seasonal change of the weight of roots in young plants varied according to the variety, the method of propagation, and the age of plant. But generally the root weight increase, remarkably from March to October. During winter the weight did not increase, though the root continued to grow to some extent. The value of T-R ratio was, as a rule, high in August and September. As the plants grow older, the ratio seemed to decline gradually. The quantity of new and fibrous roots was especially large in April and August or September. This fact may suggest a suitable period of transplanting of the plant.

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The auther has investigated morphologically the growth of seedling of nine varieties of tea plants. The seeds were sown in sand beds placed in the light and in the dark respectively. Being grown in the light, the varieties were found to be grouped into three types, according to the growth curve of the seedling, which had some relations to thc character of their mother plants. In the dark, however, each variety showed a special growth curve without regard to the group, and according to these curves we could classify the plant into three kinds viz. Indian, Chinese and Japanese. In the dark, the Indian varieties grew most rapidly, while the Chinese varieties grew slowly, and the Japanese varieties showed intermediate rapidity in the growth curve. The length of the seedlings, about three months after germination; showed also the same relations as mentioned above, either in the light or in the dark. The length and weight ratio of shoot to root varied according to the varieties more considerably in darkness than in light. The transition of the ratio during the seedling growth both in the light and in the dark were also found remarkably different according to the varieties. The anthocyanin were produced in shoots and leaves in almost equal degrees both in light and darkness. The quantity of anthocyanin produced varied conspicuously according to the varieties, and in darkness we could easily discriminate with the naked eye the degree of appearance of anthocyanin in shoots and leaves because of the lack of chlorophyll. Anthocyanin appeared on seedling in relation to the leaf color of its mother plant.

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Ipomoea batatas LAM. Kulturrasse Hitihuku 2n=90 Goldskin 2n=90 Kintoki 2n=90 Isikaja 2n=90 Turunasi 2n=90 Ipomoea pes-caprae ROTH. (=I. biloba FORSK.) 2n=30 Ipomoea pes-tigridis L. 2n=30 Ipomoea cairica SWEET (=I. palnata FORSK.) 2n=30 Ipomoea reptans POIR (=I. aquatica FORSK.) 2n=30 Ipomoea obscura KER. 2n=30 Ipomoea sp. 2n=30 Operculina Turpethum PETERS (=Ipomoea Turpethum R. BR.) 2n=30 Hewittia sublobata O. K. (=H. bicolor WIGHT et ARN.) 2n=30 Ipomoea indica MERRILL (=I. congesta R. BR.=Pharbitis insularis CHOISY) 2n=30 Calomyction bona-nox BOJ. 2n=30 Stictocardia campanulata HOUSE (=Ipomoea campanulata L.) 2n=30 Argyreia nervosa BOJ. (=A. speciosa SWEET.) 2n=30 Merremia gemella HALLIER f. (=Ipomoea chryseides KER.) 2n=58

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Der Verfasser beschaftigt sich hier hauptsachlich histologisch mit der Entwicklung der Blutenorgane einer Kulturrasse "Genji" der Suss-Kartoffel. Das Nucellusgewebe degeneriert in der fruheren Entwicklungsstufe, der Embryosack wird also spater unmittelbar vom Intogument umhullt. Der Embryosack wachst nach seiner mikropylaren Seite hin heran, indem er dort die Mikropyle erweitert. Der Sitz des erwachsenen Embryosacks ist also hauptsachlich an der Stelle der fruheren Mikropyle. Der Embryosack ist ganz normal: Synergiden 2, Eizelle 1, Polkerne 2 und Antipoden 2-3. Jede Synergide ist am mikropylaren Ende mit einem schmalen Plasmafortsatze versehen. Die Endospermbildung ist nuklear. Bei der Pollenbildung entsteht nach jeder Kernteilung der Pollenmnutterzelle eine dunnc Scheidewand, aber die Verdickung der Scheidewande schreitet erst nach der vollendeten Tetradenbildung von der Peripherie nach dem Zentrum (des Tetrades) hin fort, d. i. die Wandbildung ist sukzedan, aber die Wandverdickung ist simultan. Die Pollemwand ist mit violen zapfenartigen Exine-Fortsatzen versehen, und jeder Zapfen-Fortsatz ist von vielen feinen Stabchen-Fortsatzen umgeben. Die Austnrittsstellen del Pollenschlauche sind als runde, dunnwandige Flecken uber die Oberflache des Pollens zerstreut.

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In diesser Arbeit, war es meine Aufgabe, die biogenetischen Vrerhaltnisse des Pfefferminzols der Pfefferminzpflanzen zu untersuchen. Nach unserer bisherigen Versuche scheint es mir, als ob das Pfefferminzol auf das Wachstum derselber Pflanze irgend eine gunstig Wirkung ausubte. Materialien und Methode. Die untersuchten Pfianzen, Japanische Pfefferminze, wurden in Dezember 1937 auf dem Felde der Pfefferminzversuchsanstalt zu Kurasiki, Okayamaken, Japan, gepflanzt, und am 25te Juni 1938 und nachher geerntet. Die Sorte ist "Aka-kuki-maru-ba", die in dieser Gegend viel angebaut ist. Die Pflanzen wurden in der Hobe von 4 bis 5 cm geschnitten, und ihre Blatter wurden nach der Entfernung von dem Stengel in der folgenden Gnrppen eingeteilt. I Gruppe enthalt mur die Blatter an der Spitzen des Hauptstengels: II, die nachsten unteren ein paar Biatter: III, die folgenden ein paar Blatter: IV, V, u.s.w. (s.Abb. A) (I'=1+s+s+······). Die Destillationsapparat ist nach Wasicky u. a. ^{(13, 14)} eingerichtet, aber nach unserem Zweek wurde es etwas verandert. (s. Abb. B) Die Kapillar ist 15cm lang, aber die Inhalt betragt nur 0.5cc; did in 0.01cc eingeteilte Skala kann man bis zum O.OO1cc mit Augen messen. Wir benutzten die Alkohollampe, aber die 300 w elektrische Hitzapparat (Hitzbrett betragt im Durechmesser ca. 11cm) ist besser. 3/4 Stunden sind fur die Destillationszeit praktisch genug, wenn der Kolbenboden 1.5 cm von dem Hitzbrett entfernt ist. Die Storungen, die oft durch die Kapillarwirkung der engen Messrohre verusacht werden, werden in dieser Weise, dass vor Destillation die Kochsalzlosung bis "a" in Abb. B erfullen wird, venrrieden. Fur die Destillation ist z. B. etwa 10g getrocknete bzw. 50 g frische Material zusammen mit 150cc gesattigter Kochsalzlosung in den 200cc fassenden Destillationskolben gebracht. Nacll Beendigung der Destillation kann das Ol durch Offnen des Schiffhahnos in den kalibrierten Teil der Rohre sehr langsam gebracht. und ihr Volumen wird abgelesen. Von dem Volumen wird das Gewicht des Ols auf Grund des spezifischen Gewichts (0.87-8≒0.9 bei Pfefferminzol) gerechnet. Die Ergebnisse und Diskussion. Tabelle 1 und 2 zeigten die starke Abnahme des Prozentgehalt des Ols in der Reihe von der Blatter in der Spitzen an zu der unteren Teile des Stengels. Tabelle 3 und 4 zeigten jedoch, dass der Prozentgehalt des Ols bei der II Gruppe merkwurdigerweise grosser als bei der I Gruppe ist. Wir haben die Pfefferminzpflanzen dreimal im Jahre geerntet und untersucht. Tabelle 1, 2 und 3 zeigen die Ergebnisse des zweiten Schnittes und Tabelle 4 die Ergebnisse des dritten Schnittes. Der absolute Verlust des Ols in einem Blatt wurde gereuhnet und in Tabelle 5 angegeben. Das Zu- baw. Abnahme des. Prozentgehalts des Ols steht dem Langenwachstum der Blatter (s. Tabelle 6) in einer engeren Beziehung. Wenn man sie mit der Assimilationsmenge vergleichten, kann man aus den vorliegenden Untersuchungen ansehen, dass das Pfefferminzol die Wuchsstoffahnliche Rolle auf die Wachstum der Pfefferminzblatter spielt. Verknupft mit den oben erwahnten Ansichten, kann man angeben noch eine wirkliche Tatsache, dass das Mentholprozent des Ols nach die Alterung der Blatter zunimmt, und dementsprechend der Menthongehalt in dem Ol abnimmt. Die oben erwahnten Tatsache werden zu zukiinftigen biogenetischen Untersuchungen des Pfefferminzols otwas beitragen.

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In Japan late setting have hrretofore been occasionally used to the problem of crop rotation and irrigation facilities. The authors have carried on an investigation on the behavior of late setting in the diffrent varieties of rice. In the case when the duration of growth in seed-bed is the same, the period from time of the setting of rice seedlings to heading deer as a generally as transplanting becomes later. The number of days thus decreased varies. in different varieties, being less in early varieties than in intermediate or late varieties, as shown by our experiments (Fig. 1). We may consider that there are two different stages in the course of heading, namely, the period previous to the beginning of panicle differentiation, and the subsequent development of differentiating panicle towrds the heading, and these stages are affected by the influence of environmental factors respectively. In order to ascertain which stage will be seriously affected by late setting upon heading, the present experiments were carried out, and the results are summarized as follows: (1) The material used in this study consisted of 9 varieties with different growing periods under natural conditions. 30 days seedlings were transplanted in the paddy field on June 15th, 30th, and July 15th. In the cultivation of these varieties, the authors tried with utmost care to make all the cultivating conditions as nearly uniform as possible, so that quite uniform plants were sampled out from time to time for observation. As to the differentiation of panicle, a part of main stem inclusive of the growing point was fixed by Carnoy's fluid, cut in longitudinal section in 13μ thickness, and stained with Delafield's henmatoxylin. The differentiation of the first bract (Plate 1, (II) could be esily observed by determining the number of leaves on the main stem which were marked with enamel. The authors considered the stage in question as the beginning of panicle formation. (2) The stage of panicle differentiation may be divided into 12 principal phases as shown by the photomicrographs (Plate 1, (I)-(XII)). These 12 phases were used as basis for determining the grade of differentiation of panicles sampled at each date of observation (Table 1). After the growth of panicle were visible, their lengths were measured, and the results are shown in percentage in comparison to adult panicles (Table 2, Fig. 2, Plate 2). (3) The period previous to the beginning of panicle formation (=the number of days required from setting to differentiation of the first bract) was found to vary considerably according to different varieties and date of transplanting. This period was short for early varieties but long for late ones, and the later the transplanting, the shorter the period. The effect of late setting upon the number of days mentioned was less in early maturing varieties than in others (Table 3 Fig. 3). (4) The period subsequent to the beginning of panicle formation (=the number of days extending from differentiation of the first bract to heading) was seemed to be a little shorter in early varieties than in other ones. Notwithstanding the fact that the period in question was almost equal in early varieties both in early or late setting, it was observed to be somewhat shorter after late setting in intermediate and late varieties (Table 3, Fig 3). (5) As mentioned above, the effet of late transplanting upon the period (number of days) from setting to heading was found to be less intense in early varieties than in intermediate or late ones. This is chiefly due to the fact that the late transplanting exerts less intense influence on early varieties than on late ones concerning both perirods, viz. previous and subsequent to the beginning of panicle formation, and this effect exerts a decided influence in the formeer stage.

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