At mitosis root tip cells in I. panchananii, I. inclica and I. corornandelina (Varanasi form) show forty-four chromosomes and a fragment while plants of I. coromandelina (Lohgarha and Konark forms) show only thirty-three chromosomes and a fragment. Meiotic studies during micro and megasporogenesis of I. indica and microsporogenesis of I. panchananii show different types of chromosomal configurations at metaphase=I: many of them fail to form bivalents but aggregate in groups of two, three, four or more, where the chromosomes are joined laterally, end to end or cross-wise. Meiosis is irregular and instead of reduction division, there is an equational separation of the same number of chromosomes as are seen at mitosis. This results in the formation of two nucleate and two enucleate megaspores. A few of the larger nucleate megaspores, possibly with the full chromosomal complement, germinate and give rise to sporelings without fertilization while other larger megaspores and all smaller enucleate ones are abortive.
Triploid Rhoeo discolor exhibits various chromosomal configurations at diakinesis and metaphase-I. These are univalents, chains of from 2-18 chromosomes, rings containing from 2-4 chromosomes. Triple chiasmata is commonly observed in the triploid. Diploid Rhoeo discolor forms a circle of twelve chromosomes at meiosis. Interstitial chiasmata is reported in 2 cells in the triploid. Pollen fertility is much higher in the diploid than in the triploid. Laggards at anaphase-I and the degeneration of one or more cells in a tetrad is frequently observed in the triploid. The segmental complex formula can be explained on the basis of the complex of diploid Rhoeo, this having a circle of 12 chromosomes. A segmental formula has been evolved for the triploid in which it is supposed that the configuration at diakinesis would be a ring of ring bivalents and rod chromosomes joined together alternately.
1. The vacuoles of Phaseolus root tip cells arise by expansion of small irregular-shaped provacuoles in meristematic cells. 2. A differential staining effect obtained, together with certain morphological features, indicated that provacuoles were not derived from any other cell organelles. 3. Because of this it is suggested that one or more provacuoles persist in the cytoplasm during cell divisions, thus giving continuity to the structures. 4. Provacuoles proliferate through the cytoplasm by extension growth of the surface membranes forming long tentacle-like profiles in the cytoplasm, parts of which expand to produce more provacuoles. 5. Subsequent enlargement of these provacuoles to form the vacuole proper, involves, firstly, active growth of the membrane, and secondly, the interplay of hydrostatic factors.
On the basis of data derived from 23 individuals with abnormal Y chromosome as well as from 11 controls with the regular Y, the variation in size of the human Y chromosome was reported in a form of summary in this article. The present results indicate that the Y/F value is of some value for the evaluation of the variability in length of the Y chromosome; the Y/F index was 0.87 in the most common Y, while it exceeded 1.00 in cases with the extra long Y. Particular concern is focused upon the relation of the abnormal Y to disease states, the effect of the irregular Y on phenotype, the masculinizing effect of the Y, the localization of the masculinizing factor (or factors), and the role of the Y in sexual development in man.
During the course of the present investigation artificially produced hybrids between the different morphological types of the Dichanthium annulatuin complex and of D. annulatum×D. fecundum were analysed cytologically and morphologically so as to determine their inter-relationships. Cytological analysis of the hybrids was made and the results compared with those of their respective parents. It was observed that the meiotic behaviour of the hybrids were similar or intermediate between their respective parents. Morphological analysis revealed that the Tropical (2n=20, 40), Mediterranean (2n=40) and Senegal (2n=40) types are morphologically distinct races of D. annulatum. In geographical distribution these races overlap, and are not genetically isolated. However, their morphological identity is maintained primarily through apomixis. These three ecotypic races of D. annulatum may be grouped taxonomically under D. annulatum var. annulatum (2n=20, 40). Dichanthium papillosum and D. fecundum are isolated geographically but each overlap with D. annulatum in their natural ranges of distribution. However, these two species are closely related to D. annulatum and may be classified as D. annulatum var. papillosum (2n=60) and D. annulatum var. fecundum (2n=40) respectively. Furthermore, D. annulatumn, D. papillosum and D. fecundum together, form one interrelated agamospecies, i.e., the Dichanthium annulatum complex.
In this report, the effect of 12 non-hormonic herbicides were examined mainly on the hair cells of Tradescantia, the stipular ones of Vicia, the pollen grain mitoses of Tradescantia, the petal cells of Allium by in vivo observations, and the root tip cells of Triticurn by fixed preparations. The effects of the herbicides on the materials tested are summarized in Table 2. Among the chemicals, the effect of PCP, ATA and 3cl-IPC solutions on the mitosis induces suppressions of the spindle development in various degrees. Especially, the effect of 3cl-IPC is striking and shows coichicinelike effect. According to the reaction types, the non-hormonic herbicides except TCA are classified into four types: a) The coagulation of protoplasm occurs by the treatment with DNOSBP, CDAA, Fw-450, Fw-734 and PCP solutions in high concentrations. b) Injurious effects are induced on the metabolic cells by the treatment with DPA, CMU, CAT and ATA solutions. c) Mitotic aberrations take place by the treatment with 3cl-IPC and PCP solutions in lower concentrations and by that with ATA solution in high concentrations. d) Inhibition of mitosis occurs in MH 30 solution. In the data obtained by this experiment, some herbicides indicate significant differences on the effects at the cellular level tested between monocotyledonous plants and dicotyledonous ones.