Volume 84, Issue 1
July 1976, pages 1-36
pp 1-5 July 1976
A mixture ofLycopodium andPodaxis spores was liberated at 1·0 m above ground. Airborne concentrations were measured with miniature suction traps connected to a suction-line apparatus at three points (2·5 m, 5·0 m and 10·0 m). Their deposition on the ground was determined from horizontal microscope slides arranged immediately below each miniature trap.
The velocity of deposition,Vg, varied with distance from the source. The mean value ofVg forLycopodium (32·2µ) varied from 1·81 to 4·20 cm/s; forPodaxis (14×11µ) the corresponding values are 0·3617–0·6804. Both spore types showed a similar deposition gradient indicating that the size of the spore has no influence on the deposition pattern over the short distances tested.
pp 6-11 July 1976
The heart of the dipnoanProtopterus aethiopicus structurally resembles that of the amphibians, but its conducting system is typically piscine. The sinus venosus is thick-walled and single chambered. The atrium, the ventricle and the conus are incompletely divided, each into two parts. A single atrioventricular plug of fibrocartilagenous consistency guards the atrioventricular opening. No ventriculoconus valves are present. Ganglion cells and nerves are present on the walls of the different chambers of the heart especially at the junctional sites. Since specialized conducting tissues or cells are absent, the cardiac muscles and nerves appear to be responsible for the conduction of impulse which have their origin in the sinus venosus.
pp 12-19 July 1976
A special form of Kranz anatomy, a single chlorenchymatous bundle sheath around a central ground tissue embedding the vascular bundles, was observed to be associated with the C4 pathway of photosynthesis inGlossocordia boswallaea, a member of Asteraceae. The chloroplasts were centripetally located in the sheath cells. During short term carbon fixation, C4 acids, aspartate and malate were predominantly labelled. Radioactivity was transferred from aspartate to sugar phosphates, sucrose and starchvia phosphoglyceric acid. Enzyme activities in the leaves revealed that the plant is an aspartate forming NAD malic enzyme type. The activities of both photosystems I and II were detected in mesophyll as well as the bundle sheath chloroplasts. The findings are discussed in relation to its tropical habitat.
pp 20-25 July 1976
A haplosporidian parasite,Coelosporidium oithonae n.sp. parasitic in the body cavity of the marine copepod,Oithona rigida, is described. It is suggested that both the genera,Coelosporidium andNephridiophaga be retained, the former to include parasites of the body cavity and the latter to include those which have part intracellular and part haemocoelic development.
pp 26-30 July 1976
Twelve fungicides and two antibiotics were tested for their efficacy in controlling the spread of foliar blast and neck blast of rice caused byPyricularia oryzae Cav. in a highly susceptible cultivarCo. 13. The chemical 0-(4-bromo-2, 5-dichlorophenyl) 0-methyl phenylphosphonothioate 34% EC (Leptophos) at a concentration of lml/l of water was found effective in checking the spread of foliar as well as neck infection with a significant increase in yield. There was a negative correlation between yield and neck infection as well as yield and the spread of foliar blast. Yield was observed to be more associated with foliar blast rather than neck blast.
pp 31-36 July 1976
Nodal anatomy of 14 species belonging to 10 genera of Bignoniaceae is described. Unilacunar is the basic nodal pattern for the family with triple and multi-traced condition. The former type is observed inCampsis grandiflora, Pyrostegia venusta, Doxyantha unguis-cati, Stenolobium stans, Tabebuia pentaphylla andTecoma spp., while the latter is found inAdenocalymma alliaceum, Haplophragma adenophyllum, Jacaranda mimosifolia, Millingtonia hortensis, Spathodea campanulata, Tecoma capensis andT. jasminoides. Parmentiera cereifera has an arc of vascular elements passing through the single gap. Phylogenetic aspect of nodal anatomy is discussed.