The genera investigated were classified according to Pilger and the position of the tribes Arundinelleae, Phyllorachieae, Stipea and Aristideae in this system of classification was critized. The chromosome numbers of 79 species belonging to 45 genera have been counted. Fifty-seven of these species were recorded for the first time, or chromosome numbers differing from earlier counts were reported. The following genera were previously unknown cytologically: -Schnzidtia (n=9); Phyllorachis (n=12); Bewsia (n=10); Miscanthidium (n=10); Urelytrur (n=10); Chrysopogon (n=10) and Trachypogon (n=10). The inclusion of the genus Ehrharta in the tribe Phalarideae was criticized. It was suggested that this genus should be transferred to the tribe Oryzeae, It was also pointed out that the genus Trtrachne belongs in the Eragrosteae.
Large multinucleate and polyploid P. M. C.'s (syncytes) were observed in Erianthus arundinaceus, in Saccharum robustum, and in a S. sinense×spontaneum hybrid. Further development of these syncytes was traced as far as possible through meiosis. Syncytes previously reported in plants are classified according to whether they originated through errors in archesporial mitotic divisions, through the migration of a nucleus from one P. M. C. into another, or through the fusion of P. M. C.'s. The syncytes described in Saccharum and Erianthus are con-sidered to be cases of fusion syncyte formation. It is suggested that in Saccharum and its relatives, syncytes might lead to the formation of diploid pollen grains, and that they may play a part in the male transmission of 2n chromosome numbers.
1. The spermatogonium contains 63 chromosomes. In the serial alignment of the paired chromosomes a single V-shaped chromosome of outstandingly large size remains unpaired. The chromosome constitution of the spermatogonium comprises 62 autosomes and an X-element. 2. At diakinesis the X-chromosome appears as a heteropycnotic body. 3. The primary spermatocyte metaphase always shows V-shaped X-chromosome migrating precociously to one of the poles. 4. Some of the secondary spermatocytes contain an X-chromosome of large V-shape. 5. On the basis of the above facts, it is apparent that the present species shows male heterogamety represented by an X-O mechanism.
1. The number of nucleoli newly formed in somatic telophasic nuclei was observed in a number of rice varieties from various Asian countries. 2. In some varieties, the number of nucleoli varied from two to four from cell to cell, while in other varieties two nucleoli were found in all cells. The former and the latter varieties may correspond to the so-called “quadrinucleolar” and “bi-nucleolar” types. 3. About two thirds of the “Continental” varieties and a half of the “Tropical-Insular” varieties were of quadri-nucleolar type. In the former, the mean number of nucleoli ranged from 2.2 to 3.6. 4. All Japanese lowland Varieties were of bi-nucleolar type, while both bi- and quadri-nucleolar types were found in different proportions in other regions. 5. It was mentioned that rice might have two pairs of nucleolar chromosomes, and the nucleolus-forming power of the second pair being relative to the first, as shown by the mean number of nucleoli, might vary continuously among varieties.
Cells from the distal portion of the nephron tubule of the crayfish may be divided for purposes of description into three different regions, i.e., basal, intermediate and apical. Light microscope preparations of Bouin's fixed and hematoxylin stained material show the basal portion of the cells deeply stained and to contain fiberous like structures, oriented perpendicular to, and in contact with, the basement membrane. This method displays the intermediate and apical portions of the cells as relatively free of distinctive structure. Champy's and Regaud's methods reveal the filamentous oriented mitochondria chiefly present in the basal zone with few, if any, in the apical zone of the cells. Electron micrographs demonstrate in the basal zone of the cell a series of perpendicularly arranged lamellae extending from the region of the basement membrane to the intermediate zone of the cell. These lamellae are thought to be formed by the intricate infolding of the plasma membrane at the base of the cell. This arrangement gives rise in the spaces between the lamellae to a series of elongate cytoplasmic compartments which contain rows of short rod or filamentous mitochondria. No specific correlation of function in these cells with the presence of lamellae in their basal zone can be made, other than to state that, physiological processes are probably enhanced by the increased membrane area provided by these structures.
Azure or Feulgen positive, well-defined elements were demonstrated in the interphase nuclei of rat myeloid cells at various stages of maturation. The elements were fewer in number in more mature cells. They included two forms: namely long, fine threads and short, double-stranded, deeply stained rods. The proportion of these components varied according to maturation of the cell. The threads occurred in the myeloblasts and the promyelocytes exclusively or predominantly, while the adult granulocytes contained only rods. The former group of cells are capable of mitosis and the latter are not. The elements were similar in form and stainability to the mitotic chromosomes at the stage of nuclear reconstruction. The latter also included two forms which proportion varied according to maturation of the cell being formed, similarly as observed in the interphase cells. The similarities thus shown suggested that the chromosomal elements demonstrated in the interphase nuclei are continuants of the mitotic chromosomes.
The present investigation deals with the morphological changes in relation to the metabolic activity of tumor cells of the MTK-sarcoma III. The changes of mitochondria were traced in living tumor cells under normal and treated conditions with the aid of phase optics. The mitochondria in living tumor cells are observed as gray or black, indistinctly outlined bodies with filamentous, rod or dot-like forms. They are generally inconstant in size and number in each cell. In general, the filamentous and rod-like mitochondria are arranged in rosette form in the cytoplasm, while those of dot-like shape scatter in the cytoplasm without definite orientation. The morphological features of mitochondria were investigated in the tumor cells through a transfer generation of the tumor, in cells treated with α-peltatin, and in a heteroplastic transplantation. The data obtained indicate that the cells with filamentous or rod-like mitochondria are of high metabolic activity and that the dot-like mitochondria are of general occurrence in the tumor cells in process of disintegration or possessing lower metabolic activity.