1. Tingfan and ‘Meitan local’ varieties have been studied for pollen grain sterility. 2. Irregularities in the chromosome behaviour in meiosis have been noted and a particular mention may be made of precocious disjunction of univalents and non-disjunction of bivalents. 3. The infection of plants by virous and fungous diseases seems to increase the percentage of abnormalities in meiosis. 4. Early sowing of potato tubers has a marked influence on the general vigour of plants and thereby on the regularity of meiosis. 5. The pollen sterility in potato is probably due to an interaction between a number of different factors acting in co-ordination with each other. The present investigation was carried out in the cytogenetic labo-ratory of the National Chekiang University at Meitan, Kweichow, China, and the writer has been fortunate to avail freely of the helpful criticism and suggestions of Dr. C. C. Tan, to whom, indeed, he is greatly indebted.
The spermatozoids of March antia polymorpha and Isoetes japonica have been studied by means of the electron microscope. 1. Spermatozoids of Marchantia polymorpha: The flagellum consists of a bundle of several fine fibrils, and the semitransparent plasmic membrane surrounding this bundle was observed. The end of the flagella showed two types, a brush-like or a hook-like forms. In the hook-form, the network of the fibrils and plasmic substance were observed. The blepharoplast, the spermatozoid-nucleus, the middle piece and the plasmic region are seen homogeneous by reason of the thickness and high density for the electron beam. In the specimen treated with pepsin, it seems that the blepharoplast, the spermatozoid-nucleus and the plasmic region differ in their structure. 2. Spermatozoids of Isoetes japonica: Each of cilia consists of many delicate fibrils (about twenty in number), and the arrangements binding these fibrils near the blepharoplast were observed. The nuclear portion and the plasmic bands are homogeneous in the electron micrographs, while in the specimens treated with ammonium an expansion was produced, and the band structure and the fibrous structure which forms the bands were observed. The author wishes to express his thanks to Professors Sinoto and Yuasa for their encouragement and helpful suggestions during the course of this work. Thanks are also due to Dr. S. Okoda, Department of Radiology, Faculty of Medicine, University of Tôkyô, who kindly took the electron micrographs used in this paper. This work was supported in part by a research grant from the Fuju-kai Research Encouragement Fund.
Reciprocal translocations (RT's) induced by X-ray treatments of dormant seeds of Einkorn wheats, Triticum aegilopoides and T. monococcum, were analyzed and their chromosome constitutions established. In the attempts to combine the chromosomes into larger rings, successive crosses among the established RT-types have been carried out and all possible combinations of rings and pairs obtainable from the 14 Einkorn chromosomes were realized, resulting in a series of structural hybrids comparable with the well known situation in Oenothera. In one of the cross combinations, the crosses were so planned that the chromosomes of T. monococcum associate with those of T. aegilopoides in every ring. In this way was the (14)-monococcum aegilopoides complex heterozygote obtained. Fertility relationships and the evolutional processes of plants with ring complexes were discussed.
Zur Widerlegung der gelegentlich noch angenommenen lamellaren Leptonik mitotischer Spindeln and in Ergänzung zum polarisationsmikroskopischen Beweis ihrer fibrillaren Textur wird an Reihen von Imbibitionsversuchen mit ausgewahlten Medien der Gang der totalen and der Formdoppelbrechung der Spindeln ermittelt. Die damit erneut erwiesene fibrillare Leptonik braucht jedoch, entgegen SCHMIDT, nicht schon als beweiskräftiges Argument für die Zugfaserhypothese der anaphasischen Chromosomenbewegung zu gelten, sondern mancherlei Indizien, nicht zum wenigsten in Zusammenhang mit der taktoiden Natur der Spindel, lassen auch die Annahme von, Strömungsbewegungen als causa efficiens in der Mitose zu.