Volume 86, Issue 4
October 1977, pages 211-274
pp 211-216 October 1977
The embryo sac ofCirrhopetalum fimbriatum is 6-nucleate, generally bisporic, and occasionally monosporic. The reduction of nuclei is due to the ‘strike’ phenomenon. The two chalazal nuclei receive the micropylar polar. The secondary nucleus is triploid, and comes to lie below the egg. The embryo (in ripe seed) is undifferentiated. The cellsca, m, n, andn′ contribute to the embryo. The suspensor is single-celled, hypertrophied and cap-like.
pp 217-222 October 1977
The effects of metabolic inhibitors, thiourea, sodium bisulphite 2, 4-dinitrophenol, 2, 4-dinitrophenyl hydrazine, actinomycin-D, cycloheximide and 8-azaguanine on the nitrogen fixing heterocystous, heterotrichous stigonematalean blue-green algaWestiellopsis iyengarii were studied. In general three types of responses were discernible: an inhibition of growth in higher concentrations, partial suppression of heterocyst, and total inhibition of sporulation.
pp 223-227 October 1977
Investigations on the effect of inoculum concentration, age and degree of susceptibility of the host on bacterial leaf streak development of rice revealed that lesion length has a linear relation with inoculum concentration and inverse relation with age of the host. Susceptibility and age of the host and inoculum concentration bear no relation with the incubation period except the lowest inoculum concentrations. However, there was a definite association between method of inoculation and incubation period. Lesion colour varied with the age of the host irrespective of the inoculum concentration.
pp 229-234 October 1977
Thermal relations of the Indian leech,Poecilobdella viridis have been investigated. Leeches maintained at laboratory conditions (25·5°–27·5°C) were observed to have 36·65°C and 3·7°C as an upper and a lower lethal temperature respectively for 24 hr. Their 24 hr median heat tolerating capacity was elevated by 4·87°C after warm (32·0°±0·5°C) acclimation for 15 days. Ecophysiological significance of these changes toP. viridis in combating the ambient thermal fluxes has been hinted briefly.
pp 235-237 October 1977
Mixomicromus lampus Gen. et sp. nov. is described in this paper.
pp 239-244 October 1977
The morphology and sporogony of a coccidian,Adelina rayi n. sp. from the gut of the centipede,Rhysida longipes are described. Two types of schizogony have been observed. The macroschizonts which develop just below the basement membrane and beyond the level of nuclei of the midgut epithelium grow to a maximum size of 25·0–30·0×20·0–25·0µm and produce 80–100 merozoites. Each macromerozoite measures 12·0–13·0×1·57–2·0µm with a centrally placed nucleus. The nucleus is surrounded by a delicate nuclear membrane and has numerous small chromatin granules attached to the inner wall in addition to a single slightly larger chromatin granule placed in the centre. The microschizont reaches a maximum size of 13·0–15·0×7·0–8·0µm and produces 16 merozoites. It develops in the midgut epithelium below the level of the host cell nuclei. Each micromerozoite measures 9·6–10·6 × 1·5–2·0µm. The nucleus is centrally placed and is surrounded by a delicate nuclear membrane. The chromatin is in the form of numerous granules attached to the inner wall. No centrally placed chromatin granule in the nucleus has been observed. Association between the gametocytes occurs in the nucleus stage. The macrogametocyte reaches a maximum size of 18·0×15·0µm and the microgametocyte a maximum of 15·0×4·0µm. The microgametocyte gives rise to 4 deeply stained comma-shaped microgamates. Oocysts measure 20·0–22·0×18·0–20·0µm. They are octosporous and dizoic. The sporozoites measure 12·0–14·0×2·0–2·5µm.
pp 245-254 October 1977
The fecundity study of 80 specimens ofG. chapra from both the Keetham lake and the Ganga river system in and around Allahabad reveals that (i) the bigger-sized fish had relatively more ovarian eggs and the average fecundity value of different length and weight groups showed direct proportionate increase with the increase of the fish size. The number of eggs also proportionately increased with increase in the weight of the ovary, (ii) the two ovaries together accounted for 2·15 to 14·87% of the total weight of the fish, average being 5·67%, (iii) the average number of eggs per gm weight of fish and per 100 mg weight of the ovary were calculated to be as 947 and 1707 respectively, (iv) the various relationships involving fecundity—fish length,—fish weight and—ovary weight were found to be linear of the formy=a+bx, the linearity showed significant at 1% level, and (v) the differences were found in the mean fecundity number and the egg size between the two populations, the Keetham fish had more number of eggs of relatively smaller size than the Ganga which had less number of larger-sized ones. Thet test between the two mean fecundity showed significant difference at 5% level.
pp 255-263 October 1977
InPurana tigrina walk. the principal salivary system consists of several digitate lobes which are arranged in two sectors, viz. the cephalic sector and the thoracic sector, corresponding to the anterior and the posterior lobes respectively of the principal salivary gland of a generalised bug. All the lobes of both the sectors are similar in their histology and staining reactions. The accessory salivary system inP. tigrina is unique among insects. It consists of a very long convoluted, collapsible secretory tube which is more than thirty times longer and six times wider than the accessory salivary duct, the junction of the tube and the duct being indicated by a circlet of five binucleate unicellular gular glands. It is suggested that the tube serves the function of secretion and storage of watery saliva and the gular glands secrete certain material which in combination with the watery saliva, serves as stylet sheath forming material thereby favouring the penetration of the stylet fascicle into the hard bark of the stem during feeding operation. The existing fluid pressure in the tube and its collapsible nature are suggestive of the ejection of the fluid through the highly chitinous resistible duct at great force, analogous to the drilling fluid used in mechanical drilling operation.
pp 265-274 October 1977
The geographical distribution of 89 genera of primary freshwater fishes of India is discussed. It is shown that the fish fauna comprises three components: Indian, Indo-Chinese and Malayan, with indigenous Gondwana elements and intrusive genera. The Indo-Chinese element is dominant, whereas the Malayan element is comparatively poor. The original peninsular fauna is found as relicts in isolated hill tops where suitable ecological niches are found. There were faunal transgressions from the eastvia the Assam gateway and also from the west. The biogeography of the peninsula and the distribution patterns of the various genera are discussed. It is surmised that a major part of the fauna may have had an origin in the Indo-Chinese amphitheatre radiating and intruding in all directions. A list of the 89 fish genera is also appended.