In seedlings of Lilium Maximowiczii Regel., polyploid mitoses, Feulgenpositive bodies present in the cytoplasm, and mitotic disturbances were found. The relation between cytoplasmic bodies and mitotic disturbanes was discussed. Both mitotic aberrations and extranuclear bodies were most frequently observed at the start of germination, less frequently at later stage, and have never observed in seedlings about 1.2 cm. in length. One interpretation was given for the origin of extranuclear bodies in somatic cells. The numerical aberration of the chromosomes was found in seedlings of this lily.
The chromosomes of Mogrunda obscura (T. et S.), a species of the Gobiidae, were investigated in male germ cells throughout the course of spermatogenesis, with special reference to the sexual difference of the chromosomes. The diploid number of chromosomes was found to be 62 in the spermatogonium and the haploid number of 31 was observed in both primary and secondary spermatocytes. All the chromosomes are characterized by a simple rod-type of telomitic nature. Remarkable is the occurrence of the sex-chromosomes of the XY-mechanism found in this species. The primary spermatocyte metaphase is provided with 30 bivalent chromosomes having ordinary structure and a heteromorphic bivalent which consists of an elongate rod-shaped one connected in its extremity with a small rod-element in an end-to-end series. The heteromorphic bivalent is very prominent by lying always in the periphery of the equatorial plate along with its asymmetrical feature. In the first division the heteromorphic bivalent disjoins into two unequal components, an elongated element and a small body. In relative magnitude the larger one is approximately twice the size of the smaller one. The first division produces always two different kinds of secondary spermatocytes, despite the equal number of chromosomes, in respect to these particular elements. The history of these two particular elements was followed as heteropycnotic bodies from their appearance in the early stage of the growing period of the spermatocyte until the metaphase of the first division. This series of facts makes it most probable that these unequal chromosomes are to be interpreted as the XY-complex, the larger one being the X and the smaller the Y. This report is the first to record the cytological evidence of male heterogamety in fishes.
The karyotypes of four varieties of J. sambac and eight species were studied. The chromosomes in all the species show sub-median and sub-terminal constrictions besides being small and almost alike. The karyotype of the simple leaved species bears close resemblance to the trifoliolates than to those of the imparipinnately compound ones. In the sambacs, two groups of plants are recognized one with elliptic leaves and conical buds and another with ovate leaves and globose buds. The elliptic leaved group has longer set of chromosomes than the ovate leaved. The nucleolus was found to persist throughout mitosis in all the species and its behaviour has been described. This feature appears to be a specific character. The number of prochromosomes attached to the nucleolus at late prophase of mitosis and the number of nucleoli observed at early telophase suggest that the 26 chromosomed plants are in the nature of allotetraploids and J. angustifolium (2n: 52) an allooctoploid. J. sambac var. gunduinalli (2n: 39) and J. flexile (2n: 52) are in the nature of autopolyploids. Thus both allopolyploidy and autopolyploidy appear to have played a role in the evolution of the jasminums.
1. The potential difference (P. D.) between the two ends of one and the same internodial cell of Nitella was measured when water enters the cell at one end and goes out at the other under the osmotic gradient of 0.2M sucrose. 2. When the cell is in contact with the KCl solution in the concentration range of 0.05M-0.01M, the potential at the part where water comes out of the cell becomes always higher than that where water enters. 3. This phenomenon is explained by the uneven distribution of KCI in the cell sap in terms of diffusion potential. 4. When very diluted KCl solutions (0.001M-0.0001M) are applied to the external medium, the P. D. between the two parts of the cell shows discrepancies which are not apprehensible on the basis of diffusion potential unless changes in the mobility of K+ in the protoplasmic layer are postulated in the cell part where water flows out. The author wishes to express his most cordial thanks to Professor N. Kamiya for his helpful advice and directions throughout this work.
The course of the intra-cellular changes in a single spermatocyte of Acrydium japonicus was observed successively from diakinesis to metaphase in the living condition with the aid of the phase microscopy. Cytoplasmic precursor of the spindle body, the anchorage of the spindle poles to the cell surface layer and the rigidity of the spindle body were discussed.
1. The cytological behaviour of an unmodified diploid isolated after exposure of the control yeast, BY 1, to camphor for 90 days is described. 2. The recovered diploid is indistinguishable in its cytological behaviour from the parent yeast. As in the control, there is no synchronization in (a) the reproduction of the chromosomes, (b) the separation of the chromatids and (c) the onset of the telophasic changes, Karyokinesis and cytokinesis also do not parallel each other. 3. Rare precocious anaphases are illustrated. It is indicated how a gene mutation stabilizing the doubled chromosome complement is all that would be necessary to convert cells showing precocious anaphases into regular autotetraploids
1. A segregating population from a cross of two entries of an unidentified Tradescantia from the Edwards Plateau of Texas produced desynaptic plants in a ratio of one in ten. 2. Three desynaptic plants were found and all chromosomes were completely unpaired in the first division, however, stages earlier than diplotene were not studied. 3. No equatorial plate was formed at MI and the chromosomes were distributed to the daughter nuclei at random during anaphase and telophase. Univalents occasionally divide and both chromosomes and chromatids were frequently excluded from the daughter nuclei. 4. Dyads were normally formed but triads were found in approximately 1% of the cases. 5. The second division proceeded normally for the chromosomes included in the nuclei regardless of the number. However, those excluded in the cytoplasm as micronuclei were found to persist in an unchanged condition. 6. Tetrads, hexads and micronuclei were found in the expected frequencies. 7. Assuming a complete genome to be necessary for the first somatic division of the microspore, the expected percentage of microspores with different chromosome numbers was calculated. It was very close to the observed, but a rather large proportion of deficient microspores (2.4%) was found. 8. The microspore division was regular and except for the chromosome number, an occasional small chromosome, and one case of a telocentric half chromosome, was similar to the synaptic sister. 9. Pollen fertility was essentially as expected assuming a complete genome to be necessary. 10. The desynaptic plants were female sterile but apparently male fertile. 11. A review and discussion of the similarities and dissimilarities of desynaptic plants were made, and the relationship of all to chiasma formation noted.
The chromosomes were investigated in the subline of the Yoshida sarcoma resistant to Nitrogen Mustard N-oxide, by way of comparison with those of the original stock line. The evidence presented indicates that the resistant character is not associated with the chromosome pattern of the tumor cells. Both the original stock tumor and its subline which is resistant to the drug are conditioned by similar chromosomal situations.
This paper deals with a phase microscopy study on the effects of podophyllin on the tumor cells of the MTK-sarcoma III. The changes of tumor cells in response to exposure to the drug were followed in single cells with the utilization of the hanging-drop preparation made in combination of fluid paraffin and podophyllin. It was shown that podophyllin damaged the cells as a whole and exerted a visible influence on the cytoplasm. The cells were damaged by blebbing and vacuolization of the cytoplasm, followed by a pycnotic degeneration of the nucleus, or of the chromosomes.