Volume 64, Issue 1
July 1966, pages 1-73
pp 1-21 July 1966
pp 22-25 July 1966
The effect of 5-trifluoromethyl-2-deoxyuridine (F3TdR) on the frequency of X-ray-induced chromosomal aberrations has been discussed. F3TdR is a potent chromosome-breaking agent and its chromosome-breaking ability is concentration-dependent. F3TdR sensitizes the system to radiation and increases the frequency of X-ray-induced chromosomal aberration. The radio-sensitization is also concentration dependent. The occurrence of a large number of gaps in both chromatids and chromosomes in chemical-cum-radiation combination treatment supports the idea that the sensitization to radiation results from halogenation following the incorporation of F3TdR in DNA.
pp 26-31 July 1966
1. The ovule is anatropous, unitegmic, tenuinucellate.
2. A single hypodermal archesporial cell functions as megaspore mother cell.
3. Nucellus is consumed at an early stage of development.
4. The female gametophyte conforms to the “Polygonum type” of development.
5. At the organised embryosac stage, the integument is seven-layered thick, its inner epidermis serving as the endothelium.
6. Abnormal embryosacs with six nuclei, four at the micropylar and two at the chalazal side, have also been observed.
pp 32-37 July 1966
Dopatrium junceum Buch.-Ham. ex Benth. is a herbaceous annual species of the Scrophulariaceae. Among its important anatomical characters may be mentioned absence of root pith, Veronica type of stem stele, anomocytic stomata and homogeneous mesophyll. Profusely lacunar cortex and poorly developed vascular and mechanical tissues indicate its adaptation to an aquatic mode of life.
pp 38-44 July 1966
Some aspects of the embryology of the parasiteTetrastichus pyrillae, an egg parasite ofPyrilla perpusilla Walk., have been studied with a view to find out some of the complexities of development of parasitic insects.
In the organisation of the egg of this parasite it has been observed thatTetrastichus pyrillae does not conform to the law of orientation enunciated by Hallez (1886). It has been found during this investigation that the slightly tapering end of the parasite egg which is directed towards the head of female is definitely the anterior end bearing the micropylar opening. During development ofTetrastichus pyrillae egg it has been observed that the head of the embryo is always formed towards the broader end of the egg (Posterior). The presence of germ cell determinant at the posterior end of the egg adds to the interest of the study of this form.
pp 45-52 July 1966
The non-articulated, very little branched, simple type of laticifers inLeptadenia reticulata originate at the embryonic stage of the plant. These later on grow and develop into the other organs and form a well distributed system of laticifers, in the stem and also in the leaves, near the veins and veinlets. A qualitative chemical analysis of the latex ofLeptadenia reticulata and alsoCryptostegia grandiflora, another member of the Asclepiadaceae, has revealed the presence of various kinds of enzymes, sugars and amino-acids in the latex. These, probably, are of some importance to the plant.
pp 53-61 July 1966
Five new species of spiders are described in this paper. Most of the species were collected from Khasi and Jaintia Hills, Assam. The new species belong to four genera distributed in the family Thomisidae.
pp 62-67 July 1966
Seedling anatomy of some members of Cucurbitaceae shows two types of transitions depending upon the primary structure of the root. Six endarch bicollateral strands are formed in the upper region of the hypocotyl. These resolve into ten bundles of which four, two on either side, go to the cotyledons and the remaining six get arranged into two groups of three each. Each group of three bundles later form five and thus in the shoot there occur ten bundles, a characteristic feature of Cucurbitaceae. Cotyledonary traces and the epicotyl vasculature are related to root vasculature. Cotyledonary node is unilacunar double trace and foliar node is trilacunar.
pp 68-73 July 1966
A list of twenty-one fungi is given including one new species of whichErysiphe sambuci S. Ahmad;Puccinia prostii Moug;Uredo paspali sp. nov.;Alternaria eriobotryae Sechet andColletotrichum dematium (Pers. ex Fr.) Grove have been described. Latin diagnosis forUredo paspali is also given.