The tissues of 31 platyrrhine monkeys were studied for sex markers. A typical sex chromatin body analogous to other primates, was found in the females of all animals. The size, position, frequency, number and shape of the sex chromatin mass is essentially analogous to human tissues. Embryos of 8 and 14 weeks and full term gestation were also studied. The sex chromatin was easily recognized in the female embryos of all ages. The finding of two distinct sex chromatin masses present in cerebellar Purkinje cells of immature animals is recorded and theories as to the reasons for duplication of the sex chromatin mass, and its origin are discussed.
A phase-contrast microscopic study of pollengrain germination, nuclear movements and pollentube mitosis in Tradescantia virginiana is presented in this paper. Some of the kinetics of germination and nuclear movement have been analyzed. It has been shown that a vacuole in the pollengrain is important in pollengrain germination. Nuclear movements have been ascribed to the resultant of friction forces, together with a cytoplasmic pushing force towards the distal nuclear part. It is described how the generative nucleus passes the vegetative one and the attention is drawn to this phenomenon in order to explain the different opinions found in literature about the question, what nucleus first enters the pollentube. No evidence was found, which favours the “cell within a cell” state of the pollengrain. It is unlikely, that in the mature pollengrain the vegetative nucleus is degenerative. Some attention is drawn to possible causes of failure of pollengermination. The stages of generative nuclear mitosis have been described.
The development and application of new techniques for the study of human chromosomes has revealed that the genetics of sex determination in man appears to be different from any other system so far known. It approaches most closely that found in Bombyx and Melandrium. Despite the apparent disparity between man and other organisms the system of human sex determination may still be accommodated within the limits of a balance theory. Studies on the cytomorphology of the sex chromosomes indicate that the classical genetic map of the X and Y chromosomes is no longer valid. Tentative proposals are made concerning the structure of the X and Y chromosome. These several proposals can only be distinguished either by genetic studies on partial sex linkage or by direct observations of the meiotic behaviour of the sex chromosomes.
The development of the chloroplast from the proplastid in Liriope was investigated, using its normal, green tissue of variegated leaf as the test plant. The proplastid of normal chloroplast at the earliest stage of development is amyloplastic, containing starch granules and only a small amount of plastoplasm with a small number of scattered vesicles. With the further development of the proplastid, the vesicles increasing in number, become aggregated to constitute a prolamellar body with characteristic crystal lattice-like structure. Lamellae are formed from the prolamellar body, probably through coalescence of its vesicles. Such a primary lamellar system differentiates into grana lamellae and intergrana lamellae in mature chloroplast. In conclusion, it seems that highly ordered arrangement of lamellae arises from the regular arrangement of vesicles in the prolamellar body (crystal lattice-like structure). The author wishes to extend his heartful thanks to Ass. Prof. R. Ueda for his kind guidance throughout this work. Thanks are also due to Prof. K. Hayashi of Tokyo University of Education, and Prof. A. Takamiya of University of Tokyo for their interest and valuable suggestions.
1. The lampbrush chromosomes of Rana cyanophlyctis have been studied by phase-contrast microscopy. 2. In the fully-formed lampbrush chromosomes, the loops are large and the chromomeres so small as to be barely noticeable. In the post-lampbrush stage chromosomes, the chromomeres are more massive and fewer, whereas there are no lateral loops. 3. Chromonema is always single, but its duality is perhaps indicated by two lateral chromomeres at some positions on the chromonema. 4. Loop bridges have been encountered in some preparations. These arise through accidents of manipulation. 5. The chromomeres react positively to DNA tests, but not the loops and the chromonemata. The loops contain RNA, not found in the rest of the chromosomes. 6. Nucleoli appear to arise chiefly on a middle-size chromosome. 7. The nature of chromomeres, chiasmata and the origin of loops are discussed.
The nuclear cytology of Sphaeroplea annulina (Roth) Ag. and S. annulina var. crassisepta Heinreicher are described. Chromosome number in both the forms were determined to be 16. Earlier chromosome counts could not be confirmed. Some evidence for the possible existence of Nucleolar Organising chromosomes was presented. In its nuclear cytology, Sphaeroplea was shown to have very little in common with Cladophoraceae, while its affinities with members of Ulotrichales seemed to be close. The inclusion of the genus in the order Ulotrichales on cytological grounds was upheld.
The study was carried out in order to bring about a better understanding of the life cycle of the pteridophyte by means of experimentally induced apospory. Inducing apospory was successful in Pteridium aquilinum var. latiusculum and Dryopteris erythrosora, but the former was exclusively used in the precise study because of the rapid growth of the gametophyte and the abundant induction of apospory. The leaf or the root detached from the sporophyte produced the aposporous prothallium, but those attached to the sporophyte did not, irrespectively of the environmental conditions so far as the present study was concerned. Also the surgically damaged apex or undeveloped leaf attached to the sporophyte did not produce the prothallium. The ability of inducing apospory was limited to the early leaves or roots of the young sporophyte. The prothallial outgrowth occurred irrespectively of the leaf age and of the existence of the dividing cell. It originated from any part of the leaf without any correlation to the existing sporophytic structures, such as the leaf apex, the vascular bundle, etc. There was no polarity for the appearance of the outgrowth. Every sporophytic cell in the epidermis, the mesophyll and the cortex could produce the gametophytic cell except the guard cell and the vascular element. The outgrowth originated from one to several sporophytic cells. The first indication of the occurrence of the aposporous outgrowth was that many, large chloroplasts appeared in the sporophytic cells from which the outgrowth originated. But there were the leaves whose cells remained alive and green even after producing the aposporous outgrowth. The outgrowth on the detached root originated from the epidermis cells at or rather near the growing point. The case was essentially the same with that of the leaf. The outgrowth was morphologically and functionally a true gametophyte and bore the sex organs by which the tetraploid sporophyte was sexually produced. Neither the sporophytic nor the intermediate outgrowth occurred on the detached sporophytic organ. Also the probably tetraploid prothallium was aposporously induced on the detached tetraploid leaf. The size of some characters of the aposporous diploid prothallium, such as the nucleus, the rhizoid, the spermatozoid and the antheridium, was compared with that of the normal haploid prothallium. The former was generally larger than the latter. The tetraploid sporophyte exhibited many deviations from the normal morphology and physiology of the diploid sporophyte. They were the irregularly shaped leaf, the thick leaf, the uneven leaf surface, the dark green, the hairiness, the dwarfness, the anomalous stomata and the cold-hardiness. Each tetraploid plant may exhibit a different combination of them. There were apparently normally shaped plants too. The dimensions of the stoma and the epidermis cell on the tetraploid leaf were compared with those of the diploid leaf. The former was larger than the latter. The factors responsible for inducing apospory were also discussed. The writer wishes to express his sincere thanks to Profs. Drs. Masao Kumazawa and Ichitaro Harada of Nagoya University for their kind guidance and encouragement throughout this study, and in addition, to the latter for the correction of this manuscript. His thanks are also due to Prof. Dr. Motozi Tagawa of Kyoto University for identifying the ferns very kindly.
1. The reduction of TTC in the presence of homogenate prepared from seedlings of Phaseolus vulgaris was investigated, and compared with the reduction by ungerminated embryo homogenates. Effects of succinate and several inhibitors indicated the participation of succinic dehydrogenase in the reduction of TTC by the homogenate of the seedlings. 2. The activity of the seedling homogenate was more labile than that of the embryo homogenate. The lability was partly avoided by addition of hypertonic sucroce in the medium. The reduction was stimulated by cyanide and depressed by oxalacetate and, sometimes, excess amount of succinate. This depression was eliminated by cyanide. 3. The effectiveness of the addition of cyanide and succinate varied with the age of seedlings.
1. The first and the second internodes of spring wheat, Konosu No. 25, cultured on a medium containing gibberellin (5×10-4M) was investigated by means of X-ray diffraction technique. 2. The X-ray diffraction diagrams obtained from the control plants showed the presence of the cellulose micelles oriented in two directions crisscrossing each other at an angle of about 45° to the longitudinal axis of the stem. 3. In the diagrams of the cell walls in the plants treated with gibberellin, the cellulose micelles oriented at random showing more in an amorphous state than the cellulose micelles in untreated cell walls.