Volume 87, Issue 6
June 1978, pages 81-177
pp 81-89 June 1978
The annual reproductive behaviour of the frog,Rana hexadactyla, was studied from two climatologically contrasting regions and correlated with the environmental conditions, like temperature, relative humidity and rainfall prevailing there. Since some data were available on the gonadal activity of this species from two other areas, they were also considered. The results show that the gametogenic activity is under the marked influence of the range of temperature and relative humidity prevailing in the locality while the pattern of rainfall plays a supplementary role. The activity begins sometime in March or April when the locality experiences the pre-monsoon (south west) showers. The gametogenesis occurs rapidly around Mangalore where the range of temperature between the monthly mean maximum and the minimum is narrow and stable from April to October but in Mysore city similar environmental conditions are seen from June to October and the gametogenesis becomes active during this period. Thus, ovulation and oviposition take place during June or July at Mangalore whereas the same occur towards the end of August at Mysore city.
pp 91-104 June 1978
The embryo ofMegaderma lyra lyra enters the uterus as a morula. The blastocyst establishes contact with the uterine wall circumferentially at the level of implantation. The orientation of the embryonic mass at early stages is variable, but the flat embryonic disc at later stages is invariably mesometrially oriented. The preimplantation response of the uterus is markedly evident in the enormous expansion of the uterine glands and the hypertrophy of their cells. After the attachment of the blastocyst there is a rapid degeneration of the uterine glands and the cells of the endometrial stroma resulting in the formation of a thick zone of symplasma into which roots of the trophoblast enter. The maternal blood capillaries increase in number and their endothelial cells undergo hypertrophy. The amniotic cavity is formed by cavitation, but with the expansion of the embryonic disc the original roof of the amnion undergoes rupture and loss. The definitive amnion is formed by the development of folds from the margin of the embryonic disc.
pp 105-117 June 1978
A new genusBosostrea and its five species are described. Among other oyster species already known from elsewhere but now found occurring in the Bagh Beds,Cameleolopha cameleo (Coq.) is of particular interest bearing on the age of these beds as it comes from the Cenomanian of Algeria, andLopha (Actinostreon) semiplana (Sow.) is of interest as a species widely occurring in the Mediterranean Palaeo-Zoo-Geographic Province.
pp 119-121 June 1978
Studies on the innate capacity for increase in numbers ofHeliothis armigera were carried out at 26±1°C temperature on pea podsPisum sativum. The net reproductive rate (R0) representing the total female births was 407·39. The population increased with an infinitesimal rate (rm) of 0·1346 and finite rate (λ) 1·14 per female per day. A generation was completed in 44·64 days. The population on reaching a stable age distribution comprised approximately 99 per cent of immature stages.
pp 123-131 June 1978
The pollution studies of four rivers of Western Uttar Pradesh with reference to biological indices are reported. Physico-chemical and biological characteristics of the river water at 16 sampling points have been studied and the correlation between them have been made. It is observed that the species number (n) and the total number of organisms (N) of the phytoplankton and zooplankton, though exhibit a relationship at certain stretch with the increase or decrease of pollution intensity yet it is not found very specific and so no definite conclusions could be made. However, the quantitative and qualitative changes in the distribution of benthic macroinvertebrates are clear and specific. Benthic production is observed lower at the points having BOD below 20 mg/l, perhaps because of low availability of food, while at 110 mg/l BOD the highest benthic production (547 per Ekman grab) was observed and this may be due to the presence of good amount of food. Further, the species number (n) and organism number (N) of benthic fauna decline very much and finally disappear completely with the increase of BOD i.e. more than 310 mg/l or with the disappearance of DO (dissolved oxygen).
pp 133-136 June 1978
The copper and protein content in the blood and in the purified haemocyanin of active and aestivated snails are determined. There is a marked increase in the copper content and also in the haemocyanin content in the blood upon aestivation which is discussed in the light of the available literature. The per cent copper/protein ratio was 0·255 in the purified haemocyanin of the active and aestivated snails, suggesting similar nature of haemocyanin molecule whose minimal molecular weight was calculated to be 24,910.
pp 137-144 June 1978
The garden snailAriophanta madraspatana (Gray) was selected for pesticide bioassay in view of its seasonal abundance. Optimum conditions were standardised for culturing and maintenance of these snails in the laboratory. The studies indicated that the snails could be maintained and reared well in the wooden terrarium (54×44×30 cm) with gravel-soil-leaf medium maintained between 7 and 9 pH. The optimal temperature and relative humidity ranges were found to be 22°C–28°C and 65%–75% respectively. Out of several foods screened, germinated greengram (Phaseolus aureus) was preferred and consumed by them. Growth rate was highest in the wooden terrarium out of several terraria tested, reaching 5 gm at the end of 14th week. Snails reproduced successfully under these conditions resulting in a homogeneous population well suited for bioassay of pesticides.
pp 145-149 June 1978
The effect of epidermal secretions ofPtychodera flava collected during nonbreeding and breeding seasons on growth of two diatomsAmphora coffeaeformis andCyclotella meneghiniana is studied. Differential effect of the secretions on growth rate of the diatoms indicates differences in their potency. Low concentrations tend to stimulate growth. The ecological significance of the secretions has been briefly commented upon.
pp 151-155 June 1978
Sex ratio in populations ofPorcellio laevis (Latreille) showed that females outnumbered males in all seasons and years of study. The maximum percentage of females (69·2%) was observed during the monsoon and as the season progressed, their percentage came down owing probably to mortality among adult females. The maximum percentage of males (37%) was observed in the spring. Following mating, there was high mortality among males. The probable reasons for the low percentage of males in the population are discussed.
pp 157-159 June 1978
One new speciesDinopis goalparaensis belonging to the family Dinopidae and genusDinopis is described with notes on its habitat. This family and genus being recorded for the first time from India.
pp 161-167 June 1978
A new species of dicyemid mesozoan,Dicyemennea coromandelensis n.sp. from the renal appendages ofSepia elliptica Hoyle is described. This is the first report of a dicyemid mesozoan parasite from this molluscan host and the first from the Coromandel coast. The morphology of the nematogens, rhombogens and vermiform embryos is described and the systematic position of the new species is discussed.
pp 169-172 June 1978
Lactic acid excreted by the fish,Tilapia mossambica subjected to exercise has been measured in ambient water. The method of Barker and Summerson has been modified suitably for estimating lactic acid in the fish medium: decarbonated tap water.T. mossambica excreted 25·7, 31·1 and 31·6 mg/kg/hr of lactate at 35 cm/sec of swimming speed and 47·0, 60·2 and 54·6 mg/kg/hr of lactate at 93 cm/sec of swimming speed at the end of 1 hr of exercise at 25, 30 and 35°C respectively.
pp 173-177 June 1978
Micrixalus nudis sp. nov. is described from Wynad, S. India and compared with other known species of the genus from India and abroad. It is felt that the generic composition of the genus requires redefinition. A key to the Indian and Ceylonese species is given.