Cytological studies were carried out in three species of genus Cicer, viz; C. arietinum, C. soongaricum and C. pinnatifidum. The chromosome number of C. arietinum and C. pinnatifidum was confirmed to be 2n=16. The reported number of 2n=14 for C. soongaricum could not be confirmed and in the present material, the number was established as 2n=16. The presence of one pair of satellited chromosomes in C. arietinum and C. pinnatifidum was confirmed and instead of the reported number of two pairs of satellited chromosomes, only one pair was found in C. soongaricum. The average chromosome lengths of the different species were calculated. A significant difference in the size of the smallest pair of chromosomes in C. pinnatifidum as compared to that in C. soongaricum and C. arietinum, was found. This can be used as a distinguishing feature of the C. pinnatjdum complement whereby it can be identified from the complements of C. arietinum and C. soongaricum.

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In Gelidiella acerosa (Forsskal) Feldmann et Hamel a count of 8 chromosomes has been obtained in the vegetative cells of the thallus and a reduced number of four has been observed in the prophase of the second meiotic division of the tetrasporangium. Moreover, the characteristic “diffuse stage” or “growth stage” of the nucleus observed by many workers in all tetrasporangia undergoing normal meiosis has also been met with in this alga. It can therefore be stated that the tetrasporangium undergoes normal meiosis. The tetrasporophyte is thus a diploid phase of the plant, while the spores produced by it are haploid. Hence, there is a clear indirect evidence of the existence of the haploid sexual phase, which is the currently missing phase.

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Cytomorphological investigations were carried out in four species of Barleria and all of them showed the chromosome number 2n=40 with regular meiosis. There were significant discontinuous differences in morphology between the species studied.
The interspecific hybrid secured between B. prionitis and B. noctiflora was vigorous with profuse branches and it had a greater number and large sized flowers with a long blooming period. The hybrid had the same chromosome number (2n=40) as that of the parents and the meiosis was normal. The gross homology of the genomes of the two species is evident from the chromosome association in the hybrid. The female fertility of this hybrid was, however, considerably reduced and the causes of female sterility appeared to be complex.
The barrier to isolation in different species studied were mainly in the nature of cross-incompatibility mechanism. This mechanism appeared to be incompletely developed and reinforced by hybrid inviability.
The possibility of producing interspecific hybrids offers scope for artificial introgression. The interspecific hybrid reported herein has greater ornamental attributes than the existing forms.

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Intersubgeneric crosses were made with the newly discovered Australian species N. umbratica (n=23), with a view to find out the taxonomic position and phylogenetic relationship. The karyotype studies of N. umbratica revealed, that the species fits in the section Suaveolentes, forming a bridging link between the 22 and 24 paired species. Meiotic studies of the F₁ N. paniculata×N. umbratica showed low pairing and hence distant relationship of the two species involved in the cross. The amphiploid N. paniculata-umbratica (2n=70) is stable and bred true for 5 generations. This amphiploid supports Goodspeed's (1954) postulate, that the further expansion of the genus above 24 paired level is possible by amphiploidy.

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Zeuxine strateumatica was presently investigated with five cytotypes (2n=20, 42, 50, 60, 100). Polyploidy, though, was correlated with gigasness of the features, the different cytotypes often overlapped each other in their morphological characters. In the polyploid taxa hypo and hyper-ploid pollen cells resulted from multiple associations and non-disjunction of chromosomes and multipolar spindles.

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Ottelia from four different localities belonging to Nothern India, have been studied in the present work with the aid of improve method. Detailed study of karyotypes have been included within the scope of investigation. Special emphasis has been laid on the study of different populations of the same species to assess the role of structural alternations in the chromosomes in the evolution of different populations.
Species of Ottelia are remarkable in the sense that the populations differ with respect to the external morphology of the plant.
The diminution in chromatic matter along with polyploidy has been an associated feature of evolution in different families of flowering plants. The same is true in case of Ottelia. Hetrochromatic elimination appears to be more probable explanation for diminution in chromatic content, in this light of evidences so far obtained.

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Chromosome counts are reported for 39 collections of Gramineae representing 35 species and 24 genera.
First chromosome counts are presented for Loudetia sp., Brachiaria deflexa, B. stigmatisa, Panicum comorense, Anadelphia leptocoma, Andropogon ascinodis A. pseudapricus, Jardinea congoensis, and Sorghum lanceolatum. New chromosome counts are presented for Dactyloctenium aegyptium, Panicum maximum, Pennisetum pedicellatum, P. purpureum and Hemarthria altissima.

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The authors report the cytogenetic analysis of Neotomodon alstoni alstoni (Rodentia, Cricetidae), an endemic species restricted to the transversal vocanic system of Mexico. The chromosome number of this species is 2n=48 and the fundamental number NF=66. From the cytogenetic point of view, Neotomodon alstoni alstoni shows close relationships with the genus Peromyscus because several species of the latter show 8 pairs of biarmed autosomes as the former, as well as the same chromosome number and identical fundamental number. The analysis of male meiosis in spermatocytes shows 23 bivalents, while X and Y chromosomes having short pairing segments form an end-to-end synapsis. The X-Y complex shows negative heteropycnosis in the X component which seems to be related to their allocyclic portion during this phase of cellular cycle. The Y chromosome shows discrete positive heteropycnosis.

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In the classification of Charophytes by Wood (1962, 1964) and Imahori (1965) many taxa have been amalgamated into a system reducing their number. There is no complete support for this as revealed in our study on the four taxa of C. gymnopitys A. Br.. Cytologically they have different chromosome numbers and distinct karyotypes and are at different levels of polyploidy. These need to be given the distinction of different taxa and the names given to them by Zaneveld (1940) seem justified. Polyploidy seems to have played an important role in the mechanism of speciation in this group.

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The present study is concerned with the microsporogenesis at two different polyploid levels in two polyploids (one spontaneous and one induced) of P. longifolium, and three (two spontaneous and one induced) of P. commersonii. In P. longifolium the octoploid plants (2n=80) induced from the desynaptic tetraploid biotype (2n=40) are synaptic. In P. commersonii, the hexaploid (2n=60) and dodecaploid (2n=120) biotypes are asynaptic and synaptic respectively, while the dodecaploid (2n=120) induced from the asynaptic hexaploid biotype is completely asynaptic. The results indicate that meiotic pattern, and consequently method of reproduction, can be changed after chromosome doubling. Although the microsporogenesis in the synaptic taxa follows a normal meiotic pattern, irregularities such as the presence of univalents, multivalents, multipolar spindles, laggards, etc. are common. As a result, the percentage of pollen abortion is relatively high in these taxa. In the desynaptic and asynaptic taxa, univalents during MI asynchronously move first toward the poles and then back to the equator and the first meiotic division ends in the formation of a restitution nucleus, while the second division is rather regular. Two unreduced microspores are formed from each microsporocyte at the end of microsporogenesis with relatively low pollen abortion. The causes of modification of meiotic pattern after chromosome doubling, univalent behavior during the stage between diakinesis and equatorial grouping of univalents, and presence of anaphase II bridge in both taxa of P. longifolium were discussed.

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Growing points of four weeks old seedling of Phlox drummondii were smeared with 0.5% emulsion of colchicine in lanolin. One plant out of 20 survivors was found to be a chimera; branches developing from cells treated with coichicine showed an interchange complex of four chromosomes whilst those originating from untreated cells were cytologically normal. Cytogenetical properties of the reciprocal translocation are presented and the possible mechanisms by which colchicine could have induced the reciprocal translocation are discussed.

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Dry seeds of Trigonella foenum-graecum were irradiated at 10 to 60 KR. Germination percentage, rate of growth, pollen fertility and seed setting were investigated in M₁. Chromosomal aberration and chromosomal mosacism were noted at 40 KR. Lethals, steriles, semisteriles, dwarfs and some promising variants were isolated in M₂.

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Four species under two genera of the family Pontederiaceae have been investigated, namely, Eichhornia crassipes, Solms. (2n=32, n=16), Monochoria hastaefolia, Presl. (2n=28, n=14), M. vaginalis, Presl. (2n=1 52, II 26, III 80, n=III 40), M. vaginalis, Presl. var. plantaginea, Solms.-Laubch. (2n=52). In Eichhornia crassipes 2n=32 chromosomes and n=16 bivalents have been observed in different populations of this species. Such a regular constancy in chromosome number in a species with extensive vegetative propagation is quite remarkable. The evidences so far obtained indicate that polyploidy, aneuploidy and structural changes of chromosomes have played effective roles in the evolution of species of Monochoria. The study of the two genera shows that even though n=16 is deep seated for Eichhornia and n=13 or 14 for Monochoria the two genera certainly represent a natural assemblage under Pontederiaceae as suggested by the taxonomists. This is principally shown by their karyotypes which have remarkable similarities in the gross morphology with each other.

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Cuscuta reflexa-eine blattlose, wurzellose, parasitische Kletterpflanze-wurde als eine Kombination einiger verschiedener kürzlich ermittelter Subvarietäten erkannt. Die vorliegende Arbeit schildert die zytologischen Eigenschaften eines Zytotyps der Arten mit n=16 and 2n=32 Chromosomen, welche auf Bougainvillea glabra Chosy wuchsen. In der Metaphase variiert die Länge der somatischen Chromosomen von 10, 42 bis 23, 06μ. Der Chromosomensatz setzt sich zusammen aus acht metazentriscen, vier submetazentrischen and vier subterminalen Chromosomen paaren. Während alle subterminalen Chromosomen klar and eindeutig als die kürzesten zu erkennen sind, ergibt sich in bezug auf die anderen Chromosomen eine allmählich stufenlose Abnahme in der Gesamtlänge. Die Chromosomenpaare 1 and 2, 3 and 4, 5 und 6 etc. bis 15 and 16 gleichen sich sehr weitgehend bezüglich ihrer allgemeinen Morphologie, des Verhältnisses ihrer Arme, ihrer relativen und absoluten Gesamtlänge. Die Meiose verläuft normal mit 16 Bivalenten während der Al, mit einer regelmäßigen ungestörten Anaphase-Trennung und ergibt demzufolge eine hohe Pollenfertilität.
Da die 7 von Darlington and Wylie (1955) als die Basiszahl für die Gattung Cuscuta beschrieben worden ist, scheint es sich bei dem hier behandelten Zytotyp vermutlich um eine sekundäre Polyploidie mit 8 (7+1) als Basiszahl zu handeln. Das offensichtlich diploid-ähnliche Verhalten dieser tetraploiden Rasse wird wahrscheinlich genetisch kontrolliert. Dabei wird möglicherweise-ähnlich, wie es für Weizen beschrieben wurde-ein Gen wirksam, welches die Multivalentenbildung hemmt, somit die Paarung von 2 Homologen beschleunigt und die Möglichkeit für eine 3 oder 4-fache Paarung vermindert oder verhindert.

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Meiosis was studied in six collections belonging to four different species of the genus Digitaria. Two of these four species were studied for the first time. In another species, a new chromosome number was recorded. In the remaining fourth species an earlier known chromosome count was confirmed.
Two collections belonging to D. glauca were studied and both showed abnormal meiosis (2n=45; 2n=39). The details of meiosis in these two collections are presented and the implications of 2n=39 on the basic number in the genus were also discussed.

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The effects of the insecticide o.o-dimethyl-N-methyl-carbamido methyl dithiophosphate “Rogor” were studied on root-mitosis of Vicia faba and Gossypium barbadense. Two types of treatments were conducted: seed-soak, and root-treat. ments. Both pure and formulated “Rogor” effected a great decrease in the mitotic index of Vicia faba when compared with the control. The percentage of abnormal mitoses in beans induced by formulated “Rogor” was much higher than that induced by the pure substance. Recovery experiments showed that roots treated with pure “Rogor” recovered more rapidly than those treated with the formulated substance. Disturbed prophases, meta and anaphases comprise the most dominant type of anomalies in both beans and cotton, lagging chromosomes were also observed in both plants. Chromosome contraction was observed only in cotton. Chromosome stickiness, chromosome fragmentation, anaphase bridges, and multipolar anaphases were observed only in Vicia faba.

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It was found that RNA synthesis was markedly inhibited in Vicia faba root tip cells after treatment wi