In the former paper (Yamashina '41), the author reported the results of cytological investigations on sterility of hybrids between the Muscovy duck _??_ (Cairina moschata) and the Domestic duck _??_ (Anas platyrhyncha var. domestica). The present study deals with the cytology of the hybrids out of the reciprocal mating, Domestic duck _??_×Muscovy duck _??_. In this experiment, it was found that the hybrid offsprings of this cross posses well developed genital organs in both sexes, though they are completely infecund. Dissimilar to the former case, noticeable is that in the F₁ females from this cross there was an ovary of normal structure and an oviduct of normal size, and that they laid eggs which were much smaller than those of either of the parent birds.

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Employing the carp, Cyprinus carpio L. as the meterial, the processes of maturation of the egg and the phenomena of fertilization were microscopically observed in this study. Observations were carried on in the sections of the eggs, fixed at different intervals ranging from five minutes to 2 hours after fertilization. The majority of eggs were fixed in Carothers' solution and some were preserved in Gilson's fluid. For sectioning the Gilson material proved to be better than the Carothers material. Sections were made following the usual paraffin method. They were stained with Ehrlich's haematoxylin. The results of observations are briefly outlined as follows:
1) The first maturation division of the egg is completed prior to ovulation within the ovary. After the extrusion of the first polar body, the chromosomes remaining in the egg are immdiately drawn into the equatorial plate forming the metaphase spindle of the second maturation division (Fig. 4).
2) The spawning and fertilization take place in the water at the same time.
3) At the time of insemination the second maturation division of the egg persists in the stage of metaphase, and then it gradually advances in further course of division (Fig. 8). About 25 to 30 minutes after insemination the second division is completed, resulting in the formation of the second polar body (Fig. 9).
4) During the ovulation process the course of the second division does not proceed being arrested in metaphase. Stages subsequent to the metaphase of the second division take place only after the entry of the spermatozoon into the egg. This fact emphasizes that insemination is a necessary antecedent to the second maturation division to advance further from metaphase.
5) Only a single spermatozoon enters an egg (Fig. 7). Thus the carp egg is monospermic in fertilization under the normal condition.
6) About 40 to 50 minutes after insemination there is found at the animal pole of the egg the already metamorphosed female pronucleus. It assumes a spherical shape lying in naked state in the ooplasm (Fig. 13).
7) As early as 50-60 minutes after entrance, the head of the spermatozoon is converted into the male pronucleus attaining nearly spherical form (Figs. 10-12). At this stage there is no visible demarkation between the male and female pronuclei, so far as their structure and size are concerned. But there is present a ramarkable character peculiar to the male pronucleus. That is the pronounced appearance of the sperm-aster.
8) After completion both the pronuclei begin to move towards the deeper part of the animal pole of the egg to conjugate with each other (Fig. 14). The conjugation of the pronuclei generally takes place about 1 hour after insemination occurs (Figs. 15-17).
9) After the two pronuclei conjugate together, they do not actually fuse, but lie side by side in closs contact with the nuclear membrance intact (Figs. 15-16). Thus the maternal and paternal chromosome materials are separated in distinct groups during the stages prior to the first cleavage division. The chromosomes are formd independently in each vesicle (Fig. 17).
10) In the egg about 11/2 hours after fertilization, the first cleavage spindle is generally formed (Fig. 18).

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1. Three tetraploid hybrids obtained by crossing colchicine induced 4x-Brassica chinensis L. and 4x-Brassica napus L. were studied.
2. Chromosome numbers of these three hybrids, CNF₁-1, CNF₁-2 and CNF₁-3, were determined chiefly by counting at metaphase II to be 2n=60, 58 and 55 respectively. CNF₁-2 which had 58 expected chromosomes, showed 4-7 multivalents (chiefly quadrivalents except hexavalents in rare cases) and a few univalents. In CNF₁-1 which was hyper-tetraploid, chromosome configurations were rather complicated showing many multivalents, and as the results the chromosome distribution to metaphase II plates was very irregular. In CNF₁-3, also, multivalent chromosomes and irregular chromosome distributions were observed.
3. The appearances and the growing habits of all the three hybrids were very like that of 4x-B, napus. The percentage of good pollen grains is high but the seed fertility is generally very bad, especially in CNF₁-3 and CNF₁-1 as shown in Table 2.

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Der Verf. führt eigene Erfahrungen an. 1) Auf der ganzen Oberfläche der Iris der Neugeborenen sind die feine Blutgefässe erkennbar und es ist etwas anders als die der Erwachsenen. Im 1937 beobachtete der Verf. einen partielle Pigmentmangel der Iris bei einem Säugling im seiner 3. Lebensjahre. In anderen Fall verschwand derselben Irisbefund, wie oben genannt, in den 14 Monate.
2) Die angeborene Iridodialyse, welche meistens durch Trauma entstehen kann, wurde von traumatischen mit den Spaltlampe und Binokular-Hornhautmikroskope in einem Fall differentiert.
3) Die Pupille war dreieckig am linken und halb rundlich am rechten bei einer 40 jährigen Bauerin. Einige Falten liefen auf der Iris vom Pupillarrand nach die Iriswurzel. Es wäre vermutlich angeborene Anomalien der M. sphincter pupillae, weil kein andere ätiologische Moment anerkannt würde. Die 2 unter den 3 Geschwester nach dem zweimal wiederholten Heiraten zwischen Vetter und Basen in den 4 Generationen litten an Cataracta congenita, welche als die auf Heiraten in den Blutverwandten stützende anerkannt würde, da die andere Ursache dafür nicht gefunden wurden. Im 1935 untersuchte der Verf. 2 Stammbäume von vererbten Schielen. Es stelltee je 4 Sehielfälle unter den 128 Mitgliedern in den 5 Generationen beim ersten Stammbaum und unter den 35 Mitgliedern in den 4 Generationen beim zweiten fest.
4) Im 1929 beobachtete der Verf. 2 Fälle von Cataracta congenita mit Kryptorchismus. Die embryonale 6. bis 7. Monate sind im Uebergang des 2. zu 3. Stadium der Absteigung der Hoden und anderseits im Involutionsstadium der Tunica vasculosa lentis und A. hyaloidea. Die Störung der Absteigung der Hoden (Kryptorchismus) und Ernährung der Linse (Cataracta congenita) können in diesen Stadium verursacht werden. Der Verf. kann noch einen Fall derselben Art, “angeborene Anomalie der Iriskrause mit Hypermetropie” anführen. Es ist nicht klar, ob in der embryonalen Zeit zuerst der Circulus arteriosus iridis minor sich entwickelt (am Ende des 6. Monates), woran dann die Membrana pupillaris haftet (in den embryonalen 3.-8. Monate), um die Lage der Iriskrause zubestimmen, oder umgekehrt. Jedoch die in den innigen Verhältnissen mit der Refraktion stehende Sklera versieht mit nahezu allen Elemente des embryonalen Gewebes im 5. Monat und nachher entsteht Hypermetropie durch Anomalien der Vergrösserungsvorganges der Sklera. Mit der Entstehung der Hypermetropie sei diese Lageanomalie der Iriskrause durch den abnormalen Vorgang gegen dem embryonalen 6. Monat zu entstehen.
5) Beim Säugling beobachtet der Verf. häufig angeborene Verstopfung des Tränenweges, dessen Strörungen durch nur das einmalige Drücken mit der Fingerspitze oder Sondierung beseitigt werden. Das ist ein Beispiel, die Strörungen der leichtgradigen angeborenen Anomalie durch verschiedene Behandlung bessert werden. Im 1940 vom diesen Standpunkt aus veröffentlichte der Verf. seine Arbeit “Experimentelles über die therapeutische Anwendung der Chronaxie, I. Kondensatoren-entladungs-Therapie der Netzhaut”.

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The Japanese Silky fowl is quite remarkable in being polydactylous generally having five toes on each feet.
In the cross between the Silky fowl and White Leghorn breed having four toes, the inheritance of polydactyly was studied in this work.
1) The F₁-offsprings obtained from the Silky fowl×White Leghorn showed to be always polydactylous without exception (see Table 2).
2) In the F₂-generation, polydactylous fowls and normal fowls were produced in the ratio of approximately 3:1 (see Table 3).
3) Segregation in the FR₁-generation (back-cross) was found to be polydactyly, 1: normal, 1 (see Table 4).
4) From the above results obtained, it is evident that the polydactylous character has been inherited as a Mendelian, autosomal dominance, so far as the scope of the present experiment is concerned.

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