1. In the present research, cytogenetical studies on the F1 plant raised from T. polonicum×S. africanum were carried out in meiosis of PMC's. 2. In general, the external characters of F1 plant resembled to the parents, but more closely to T. polonicum as the mother plant (Photo. 1). 3. At the heterotypic metaphase in meoisis of PMC's of F1 plants, 03 bivalents or 1521 univalents were observed (Table 2). The bivalents may probably be made by autosyndesis between the chromosomes of AB genomes of T. polonicum. 4. The F1 plant has the property of self pollination as in T. polonicunm used as the mother plant. 5. The F1 plant shows some fertility in natural selfing though lower in percentage (Table 1).
1. The submicroscopic structure of the carp erythrocyte has been studied on ultrathin sections. The material was fixed in buffered (pH 7.4) osmium tetroxide solution and embedded in n-butyl methacrylate. 2. The osmiophilic body in the cytoplasm seems to be the Golgi apparatus which is connected with the nucleus and cell membrane through the tubule. 3. The nucleus surface is characterized by drumstick-like processes protruding into the cytoplasm. 4. The nuclear membranes are observed as double layers, a porous external one and a compact internal one. 5. The heterochromatin appears as dense bodies attached to the coiled euchromatic threads. 6. The metabolic chromosome in the carp erythrocyte nucleus is composed of coiled filaments with a pitch of 20-40mμ and a width of 10-20mμ.
1. Somatic chromosomes of sixty eight species found in Japan and in some foreign countries were reported (Table 1, Figs. 1-67). They belong to forty four genera in fourteen tribes, i.e. Hordeum, Hystrix, Elymus, Agropyron, Lolium, Bromus, Briza, Festuca, Poa, Glyceria, Torreyochloa, Agrostis, Calamagrostis, Koeleria, Deschampsia, Arrhenatherum, Holcus, Brachyelytrum, Stipa, Phaenosperma, Hakonechloa, Pleioblastus, Sinoarundinaria, Pseudosasa, Sinobambusa, Sasamorpha, Semiarundinaria, Arundinaria, Sasa, Cleistogenes, Muhlenbergia, Eragrostis, Zoysia, Cenchrus, Setaria, Oplismenus, Paspalum, Andropogon, Bothriochloa, Pseudopogonatherum, Sorgum, Ischaemum, Phacelurus and Coix. 2. Torreyochloa natans, which had no cytological study up to now, showed fourteen medium or somewhat large chromosomes, differing from those of Glyceria (cf. Church 1949). 3. Deschampsia caespitosa obtained at Mt. Hotaka had twenty seven chromosomes in somatic cells, one being very small chromosomes in contrast to the others and twenty six ordinary ones. 4. In Koeleria cristata, among thirteen individuals studied, one individual collected in Tokyo showed fifteen somatic chromosomes, one being very small chromosome in comparison with the others and fourteen ordinary ones, and the other individuals showed sixteen chromosomes, two being very small chromosomes and fourteen ordinary ones. 5. Twelve species of Bambuseae observed all showed forty eight chromosomes in somatic cells. 6. Paspalum dilatatum showed fifty chromosomes in somatic cells, in agreement with Krishnaswamy's (1940) observation, suggesting a basic number of five in Paniceae. 7. Karyotaxonomic information concerning the genus Brachyelytrum was mentioned. The writer wishes to express his cordial thanks to Dr. Y. Takenaka, Dr. J. Ohwi and Prof. Dr. H. Ono, who gave him various valuable advices and helps during the course of the present investigations. The writer's thanks are also due to Dr. S. Matsumura, Dr. R. W. Pohl and Mr. S. Nakao, who kindly sent or offered materials for the writer's use, and to Prof. Dr. K. Dan and Dr. J. Dan for their kindness in reading the manuscript.
1) The central body of the silkworm was traced in unbroken continuity from resting spermatogonia to spermatids, and the observations were compared with those in other animals. 2) Each spermatogonium exhibits a centrosome, which consists of an idiozome and a pair of short rod-shaped centrioles at the midst of the idiozome. 3) At the beginning of the growth period of the primary spermatocyte, each centriole divides into a pair of globules, so that two pairs of spherical granules are produced in each cell. At the second contraction stage, the centrioles move out of the idiozome into the area between the cell surface and the idiozome. The four centrioles elongate into elliptical or rod-shaped bodies, each extruding an axial filament from the distal tip and they are frequently in contact two by two at the proximal tips, forming two V's. The idiozome disappears in the dispersion stage. By the diakinesis stage, the centrioles divide again into four pairs of spherical granules. Thus, two pairs of spherical centrioles are distributed to each pole of the first maturation division. 4) During the telophase and interkinesis, the two pairs of centrioles separate and move until they reach the positions 180° apart, so that a diplosome is found at each pole of the second maturation division which is distributed unchanged to each spermatid. 5) It is most significant that the centrioles increase in number up to the diakinesis stage to become as many as in all four spermatids together, and so the total amount of centrioles remains unchanged throughout the two meiotic divisions, in marked contrast with the somatic divisions. This relation is in agreement with the majority of extensive observations carried out by many authors on various animal species.
Es wurden die Mischungs- und Entmischungsmöglichkeiten der plasmatischen Erbträger im Modellversuch bestimmt und theoretisch unter der Voraussetzung berechnet, daß bei der Vermehrung der plasmatischen Erbträger ihre Zahl je Zelle konstant bleibt und daß die Erbträger bei der Zellteilung zufallsgemäß auf die Tochterzellen verteilt werden. Aus den erarbeiteten Zahlen ergeben sich wichtige Hinweise über die Gesetzmäßigkeiten der intraindividuellen Plasmon-Umkombination, über die Entmischungsgeschwindigkeit, über die Plasmonzusammensetzung vor, während und nach der Umkombination und über die Bedingungen, unter denen Plasmonmutationen aufgefunden werden können. Da die Entmischungsgeschwindigkeit der plasmatischen Erbträger nach Mutation oder Plasmamischung während der Befruchtung wesentlich von der Zahl der plasmatischen Erbträger bestimmt wird, so läßt sich aus der Art eines genetischen Musters die Zahl der maßgeblichen Erbträger je Zelle bestimmen. Damit wird die Lokalisation einzelner Plasmafaktoren möglich. Im Falle einiger mütterlich vererbter albomaculata-Schecken ließ sich durch Fehlen von Mischzellen und aus dem verspäteten Auftreten der Schekkungen nachweisen, daß diese albomaculata nicht durch die Erbträger der Plastiden bedingt sind sondern durch Erbträger, die in wesentlich größeren Zahlen je Zelle vorkommen. Es wird eine Vererbung durch die Sphaerosomen vermutet.
The action of ethyl urethane on mitosis and meiosis in male grasshopper Poecilocera picta has been studied. A 0.2M solution in water injected into the body cavity induces very striking changes. Among the qualitative effects are supercontraction of mitotic chromosomes, stickiness and liquefaction, chromosome fragmentation and polyploidy. The cytoplasm too shows inability to divide and the spindle is also affected. Tripolar spindles are quite common. Perhaps the most interesting change is brought about in meiosis, where in a large percentage of first anaphase figures, the bivalents do not separate into their univalents but bodily move to the poles. This segregation of bivalents would seem to indicate a change or an upset of the centromere-spindle-centrosome mechanism. Dissolution of sperm heads is also seen. An analysis of the division stages reveals that urethane has changed frequencies of stages in mitosis and meiosis. In the grasshopper, unlike other organisms, prophases are affected and a very large percentage of them are destroyed. Consequently metaphases are fewer. Similar observations are made in meiosis also where prophases undergo extensive damage. First anaphases, however, appear to increase in number, consequent on their blocking. Metaphases also increase for the same reason.
The available information concerning the effect of the anesthetics, and migration of potassium in the primary pulvinus of Mimosa pudica may be summarized as follows. 1) Ether and urethane may be of no efficacy on the salts distribution of the living cells. And it may be deduced that these narcotics give no remarkable visible effect upon the protoplast of the motor cells. 2) 0.2M concentration of ethyl urethane causes the reversible anesthetic effects in the motor organ. 3) The plants were anesthetized in ether vapour or by absorbing the urethane solution through the stem. In both materials there are no differences in the sponogram. 4) When the ash image of two conditions, before and after receiving stimuli, are examind, the migration of salts from the motor tissue-cells to the phloem is clearly observed. 5) Parallel to the microincineration, the micro chemical technique for potassium were undertaken. The materials before receiving stimuli are subjected to Macallum's modified solution. By this technique crystals of potassium salts are found in the motor cells. After receiving stimuli, large crystals appear in the large intercellular spaces. From this data it can be supposed that the potassium solution in the motor cells permeates into intercellular spaces at the bending movement. This phenomenon suggests that the permeability of the cytoplasm against potassium increased at the bending movement and its recovery. 6) On the transitional zone, between the pulvinus and the stem and between the pulvinus and the petiole, the large parenchymatous cells and intercellular spaces are arranged lengthwise. In this transitional tissue, potassium solution passes through at the bending movement. 7) The migration of potassium solution may be summarized as follows; Motor cellus→intercellular spaces→transitional tissues.
When roots of Vicia faba are immersed in a solution of a thymine analogue, 5-aminourcil, 50 ppm. chromosome aberrations are induced at anaphase. Among these are chromosomes which are bent so that a polar group has a bell-shaped outline, chromosomes which disjoin faultily and chromosomes which contain with increased frequency regions devoid of material stainable with the Feulgen procedure. Sites of differential response (Feulgen-negative regions in the terminology of Duncan and Woods) have recognizable locations. They lie in or near regions which other authors have identified as heterochromatin. The frequency with which these sites become Feulgen-negative is highest in roots treated with 5-aminouracil for 12 hours, lower in roots treated for 24 hours and lowest in control roots and roots which are recovering in distilled water 24-48 hours after removal from a 24 hour treatment with 5-aminouracil. The change in frequency from 12 to 24 hour treatments constitutes a partial recovery. In roots treated with a mixture of 5-aminouracil 50 ppm. and cytidine sulfate 126 ppm. the frequency is intermediate between that of control roots and of roots treated with 5-aminouracil alone. The Feulgen-negative regions, therefore, are considered segments of chromosomes where interference in pyrimidine metabolism is critical, an exogenous source antagonizing the antimetabolite 5-aminouracil. Other aberrancies induced by treatment with 5-aminouracil are less intense. Since comparable sites of sister chromosomes at anaphase are often similary affected and since Feulgen-negative regions can be demonstrated in metaphase chromosomes, a preanaphase cause is indicated. Their incidence in roots treated with 5-aminouracil is highest when the mitotic index is lowest, a fact associating their origin with inhibition of DNA synthesis. DNA synthesis, of course, occurs during interphase. Perhaps initiation of Feulgennegative regions is an aspect of its interference in DNA metabolism.