Cytological studies made for the first time in C. augustum have shown 2n=22 chromosomes while in C. rattrayii a triploid number (2n=33) has been found. The finding of 22 somatic chromosomes for C. amoenizun and C. asiaticum by previous workers have been confirmed. Two apparent polyploid series-one starting with 6 and the other with 11 as the basic number have been suggested for this genus. The need for extensive cytological studies and hybridization work in order to know the nature of polyploidy and speciation in Crinum has been stressed.
The development of the Golgi body during the microsporogenesis of Tradescantia paludosa was observed by use of an electron microscope. It was found that all the Golgi bodies develop more or less synchronously in the pollen mother cell, in the microspore after meiosis, and in the pollen grain after postmeiotic mitosis. The youngest form of this organelle is a single ring-cisterna. The organelle enlarges by addition of other concentric cisternae. These arrays open out to form a stack of parallel and straight cisternae, which later decreases in number by vesiculation. As the synchronous development of the Golgi bodies is followed by simultaneous degeneration, three generations of the Golgi bodies are recognizable during the formation and development of the pollen grains; the first generation is found in the pollen mother cell, the second in the young microspore, and the third in the pollen grain after the postmeiotic mitosis. The change in generation of the organelle takes place during mitoses, namely during meiotic mitosis and postmeiotic mitosis. In somatic cells such as root meristems, elongating zone of roots, and stigmas as well as in the sporogeneous cells in young anthers, there are various forms of the Golgi bodies in the same cell, indicating that the Golgi bodies do not develop synchronously. Their synchronous development during the formation of pollen grains is, thus, a striking incident, which starts from preleptotene of meiosis.
1. The present paper deals with the cytological investigations of the two marine spp. of Cladophora, C. Hutchinsiae Harv, and C. refracta Aresch. which were collected from the British sea-shores in 1956. 2. The detailed morphological characters of these two spp. have been studied. The plant material of C. Hutchinsiae Harv. fits the figure and description given by Harvey (1846-51, plate XXIV), Dillwyn (1809, plate 109) Kützing (1853-54, Tab. 87, Fig. 1). The width of its main filaments agrees with the diameters given by Hauck (1885, p. 453), DeToni (1889 p. 314), Setchell and Gardner (1920, p. 213) Collins (1928 p. 265) and Newton (1931 p. 82). 3. The diameter of main filaments and ramuli of C. refracta Aresch. agrees with Newton (1931, p. 85); but the cells of its main filaments are found sometimes up to 6 times as long broad. 4. Quadriflagellate zoospores and biflagellate gametes have been observed to be produced from similar but separate plants of C. Hutchinsiae Harv. Both types of swarmers vary in shape and size with those of the zoospores and gametes that have been observed by the author (1963) in C. flexauosa Harv. 5. Biflagellate gametes have been observed to be produced from C. refracta Aresch. The gametes of this plant also vary in shape and size of the gametes of C. Hutchinsiac Harv. and that of C. flexuosa Harv. 6. Stages of meiosis and mitosis have been studied in C. Hutchinsiae Harv. If meiosis precedes zoospore formation, this species appears to be a diploid one and possesses a life cycle showing isomorphic alternation of generation as was observed by the authors (1963) in C. flexuosa. C. refracta Aresch. under investigation appears to be a haploid species in which the production of gametes only have been observed. 7. In C. Hutchinsiae, the number of chromosomes has been estimated 24 from the mitotic metaphase which is the diploid number of this species. The number of 12 bivalents has been estimated during meiosis. In C. refracta 12 chromosomes have been counted from the mitotic metaphase, this being the haploid number for this species. 8. The chromosomes show localised median and sub-median centromeres like most higher plants. Each meiotic bivalent shows either one or two chiasmata and the meiotic divisions do not differ essentially in its particulars from those in the higher plants. 9. The present two spp. C. Hutchinsiae Harv. and C. refracta Aresch. differ from C. flexuosa Harv. and also from each other in the size of chromosomes, nuclei and also in the dimension of the swarmers, besides the dimension of the filaments and the types of branchings. 10. Microphotographs have been produced in support of the evidence of the presence of nucleoli and their dissolutions the presence of chromocentre like bodies and the choromosome counts from mitotic and meiotic divisions. 11. The method of staining by acetocarmine has been used for cytological study.
The effect of 0.1% colchicine administered by two different ways upon the testes cells of the grasshopper, Spathosternuyn prasiniferum has been studied. The colchicine treatment produced different kinds of changes in the division apparatus as well as on the morphology of the chromosomes. Qualitatively both the kinds of administrations produced similar types of abnormalities in the spermatogonial and spermatocyte cells. The different types of abnormalities observed have been described under four general headings:-1) mitotic changes-changes in the spermatogonial metaphase stage and in the testes sheath cells, 2) changes in the meiotic prophase stagescytoplasmic fusion to form multinucleate cells, failure of synapsis, reduction of chiasmata, and failure of spindle formation etc., 3) changes in the first and second spermatocyte metaphase stage-C-mitotic metaphase at metaphase II, breaking down of spindle, star or ball metaphase, grouping of chromosome disposition, sticky connection, multipolar spindle etc., 4) post-metaphase abnormalities-unoriented chromosome dispostion, asynchronous chromosomal division, lagging chromosomes, sticky chromosomes, pycnotic chromosomes etc. Quantitatively the food administered series did show more effect in the cells than that of the injection series. The types of changes observed commonly in the treated series were not observed in the control series. The quantitative analysis of some types of abnormalities such as C-mitosis, polyploid cell, polynucleate cell and cell with destroyed spindle revealed that the frequency of abnormalities increased with the prolongation of post-treatment fixation hour except for the frequency of C-mitotic cells in injection series and polyploid cells in the food administered series. The results have been discussed on the relative efficiency of different kinds of administration. Further, it has been revealed that the colchicine effect on the cells is enhanced with the extension of post-treatment fixation hour and the meiotic chromosomes seem to be more susceptible to colchicine effect.
Maize samples of plants from siblings of open pollinated populations from all parts of Italy have been cytologically investigated. It has been found that the amount of heterochromatin is on the increase in all parts of Italy but more so in the central regions. New knob forming segments have been located and their origin is thought to be from de novo formation of knob substance. In the course of meiotic studies several chromosome aberrations have been observed. The rates of spontaneous mutation has also been investigated. These rates are higher in the south than north while in the center it is medium. Contrariwise the amount of heterochromatin is higher in the north and lower in the south. In view of this the frequency of spontanous mutations observed in supposed to be partly due to heterochromatin differences and chromosome interaction and partly due to chromosomal aberrations. The possible role of heterochromatin in the structure and function of maize chromosomes has been discussed. The influence of spontaneous mutations and the changing pattern of heterochromatin have been mentioned in relation to evolution of maize in Italy.
Some of the spontaneous chromosome aberrations and abnormal behaviour observed in the meiosis of sibling plants from open pollinated Italian maize populations have been reported. It has been found that the frequency of chromosome breaks and other aberrations in this material is rather very high. In one case the chromosome aberrations are accompanied by visible morphological “mutation”-dioecious inflorescence-tassel-ear type. Various other abnormalities such as pachytene pairing failure, secondary association at metaphase and univalent and multivalent formation, differences in the length of satellite segment on chromosome 6 and differential contraction of heterochromatic segments and their effects on general chromosome behaviour have been discussed. The importance of heterochromatin in all these aberrations has been stressed.
The karyotype analysis was undertaken in six members of the Ranidae based on current technique with adult bone marrow cells, with special regard to the relationship between the karyotype and taxonomical feature. Karyotypes of two subspecies of R. tenzporaria temporaria and R. t. ornativentris were basically identical with each other. The karyotypes of R. Japonica, nigronzaculata, rugosa and catesbiana were generally similar from one another in both number and morphology, though two identifiable features were found to occur in nigroznaculata and catesbiana. Comparison of the karyotypes in both sexes demonstrated no significant morphological difference, no heteromorphic pair having been detected either in males or in females.
1. By using the dilute acridine orange solution as a fluorochrome, the developmental process of the spindle body and the chromosomal fibers are investigated in vivo in pollen mother cells of Lilium longiflorwn; through such specific treatment secondary fluorescence has been demonstrated. 2. The transition of nuclear substances into atractoplasm, the nature of the chromosomal fibers and the fibrillar structure of the spindle body have been discussed based on their fluorescent tints. 3. The applications of this technique on mitotic cells are excellent to elucidate the relationships between the morphological changes of cellular elements and the chemical ones of their constituents in a mitotic cycle.
Well-defined spindle figures are observable in the pollen mother cells of Zingiber Mioga under ordinary light as well as polarized light microscopes. The spindle is characterized by its large size and sharply pointed poles and also the presence of a spindle membrane, the chromosomal fibers, the distribution of spindle unit fibrils, and their independency in the cell are obviously demonstrable. These excellent characters in the meiotic cells of Zingiber Mioga are available to analyze the entity of the spindle body morphologically and biochemically in future.
Osmiophilic inclusions were observed in the alveolar epithelial cells of the hog lung. In many cases, the osmiophilic inclusions appear as myelin figures. The osmiophilic inclusions bear a striking resemblance to osmiophilic material washed from hog lung in the form of bubbles. The general similarity could indicate a direct relationship between the inclusions in the alveolar epithelial cells and alveolar lining substances. In the washed bubbles, a lamellar structure was revealed which indicated a repeat unit of 95Å.