Volume 39, Issue 3
March 1954, pages 91-132
pp 91-99 March 1954
Three instances of heavy fish mortality in the Virudhunagar quarry fish farm in Madras State are described. Oxygen depletion in the waters, especially during night and early morning hours, has been found to be responsible for the mortality in all of them. The oxygen deficiency in each case was traced to an excessive growth of green micro- and macro-vegetation which disturbed the biological balance, normally controlled by photosynthesis, respiration and bacterial decomposition. The deprivation of dissolved nutrients for the plants owing to the thermal stratification and absence of turnover in the fish farm was responsible for the death of the plants, the decay of which also contributed to a faster depletion of oxygen. The recurrence of such disasters to fish in farms can often be prevented by controlling the growth of micro- and macro-vegetation.
pp 100-113 March 1954
The presence of the extra-cellular enzymes cellulase and cellobiase, has been established in the gut extract of the higher termiteTermes (Cyclotermes)obesus (Rambur).
The activities of both these enzymes have been found mainly in the hindgut of the termite, where bacteria are mostly harboured. It appears that the enzymes are derived from these bacteria.
Cellobiase has a sharp pH optimum at 4·0 while cellulase has an optimum pH range from 3·8 to 4·4. The optimum temperature is 30° C. and 38° C. for cellulase and cellobiase respectively. Both the enzymes are heat stable, cellobiase being more so than cellulase.
The extent of activity of these enzymes in various castes other than workers has also been studied and a possible mechanism of digestion has been suggested.
The action of termite cellulase on certain cellulose ethers has been studied.
Zinc and chromium (at 0·1 M concentration) suppress cellulase activity almost completely but cellobiase activity only partially.
pp 114-117 March 1954
pp 118-127 March 1954
A new marine member of the Euglenineæ,Protoeuglena noctilucæ gen. et sp. nov., is described in detail. The euglenoid occurs in very large numbers inside healthy and activeNoctiluca miliaris Sur. individuals which consequently appear green. SuchNoctiluca individuals occur in swarms frequently colouring the sea green in patches. The euglenoid is very simple in its structure. It is pear-shaped with a broad anterior end and a narrow posterior end and possesses a single flagellum, a single green plate-like chloroplast, a paramylon granule in close apposition to the chloroplast. And it shows a slight depression at the middle of its anterior end. This depression (invagination) very probably represents the beginnings of a gullet. It reproduces by longitudinal division. It appears to be a very primitive member of the class. Its association withNoctiluca appears to be symbiotic. It is suggested that this euglenoid is a most primitive member of the Euglenineæ coming very close to the ancestral type from which the rest of the Euglenineæ have been derived.
pp 128-132 March 1954
The development of the microspores is of the simultaneous type. The haplojd number of chromosomes is 28.
The pollen grains are binucleate at the shedding stage.
The ovules are anatropous and bitegmic. The nucellus is massive.
The archesporial cell arises in the fourth layer of the nucellus and directly functions as the megaspore mother cell.
The development of the embryo-sac is of thePolygonum type. The antipodals are ephemeral.