Volume 65, Issue 5
May 1967, pages 175-230
pp 175-180 May 1967
The shoot apex ofPicea smithiana (Wall.) Boiss. shows five distinct zones; the apical initial group, the subapical initial group, the rib meristem, the surface layer and the flanking zone. The apical initials are large cells with prominent nuclei. The subapical initials are derived from the apical initials. They contribute to the rib meristem and the flanking zones. The rib meristem consists of highly vacuolated cells with a definite pattern in the shoot apex. The cells of the surface layer undergo periclinal divisions during leaf initiation. The flanking zone is with smaller cells and is the site of procambium initiation.
pp 181-184 May 1967
The presence of large banded polytene chromosomes in several larval tissues of mosquitoes offer a unique material for cytogenetic and evolutionary studies. This paper presents a brief description of the salivary gland chromosomes in four tropical anophelines studied for the first time.
pp 185-191 May 1967
pp 192-199 May 1967
The effect of viomycin on RNA, DNA and protein content ofAerobacter aerogenes has been investigated on normal strain with increasing concentrations of the drug, trained culture and reverted culture obtained by passaging the adapted strain hundred times in the drug-free medium. Variations of RNA, DNA, protein content and RNA/DNA ratio have also been reported.
pp 200-209 May 1967
Two new species of the genusGlossimetra Mehra, 1937;G. tamiansis n.sp. andG. narmadai n.sp. are added. The genusGlossimetra is discussed in detail and amended. Its relationship withSpinometra Mehra, 1931, is described. The paper also includes key to species of the genus.
pp 210-220 May 1967
The flowers are polygamous, epigynous, tetramerous and actinomorphic. The anther wall consists of an epidermis, an endothecium, 2–3 middle layers, and a glandular tapetum. The tapetum is uninucleate and rarely becomes baseriate. The middle layers degenerate when the endothecial cells develop fibrous thickenings. The epidermis becomes discontinuous in the dehiscing anther. Cytokinesis in the microspore mother cells is simultaneous. The pollen grains are shed at 3-celled stage.
The ovules are anatropous and bitegmic. A group of nucellar cells lying immediately above the vascular supply become cutinized in the mature seed and forms the hypostase. The development of the embryo sac corresponds to the Polygonum Type. The antipodal cells show enormous increase in size and persist upto the late globular stage of the embryo.
The primary endosperm nucleus divides only after the division of the zygote. The endosperm is ofab initio Cellular Type. The embryogeny conforms to the second period, megarchetype III, and group I in series A′ of the system of embryogenic classification of Souèges, and corresponds to the Myriophyllum variation of the Caryophyllad type.
pp 221-229 May 1967
The apical growth of the leaf primordium is augmented by apical and sub-apical initials. The development of the laminal complex takes place in three steps; the primary, secondary and tertiary. The primary laminal growth is connected with the organization of submarginal and marginal initials. The cessation of meristematic activity in the primary lamina is followed by the appearance of an intercalary meristem at its base. The activity of the intercalary meristem results in the formation of the secondary lamina, which later connects the primary lamina with the rachis. A major part of the laminal complex is the ‘composite lamina’ produced by the juxtaposition of primary lamina and secondary meristem as a result of differential abaxial expansion of the latter. The composite lamina alone develops Haut which is identical with the juxtaposed primary lamina. The primary lamina (the Haut and reins) is functionless and shrivels up at late stages. The protoderm of the leaflets is regenerated from the split surfaces of the secondary meristem from which alone the pinnae are derived.
pp 230-230 May 1967 Erratum