Volume 33, Issue 3
March 1951, pages 101-164
pp 101-124 March 1951
The available information on the life-history ofHilsa ilisha (Ham.) is given briefly and discussed. The collections of eggs and early larvæ from the Hooghly River in West Bengal and from the Daya River (Orissa) are recorded. The spawning habits are given. The unfertilized egg which is 0·70 to 0·75 mm. in diameter, is almost spherical, transparent and demersal though it contains many oil-globules. A fair-sized femaleHilsa is estimated to contain 1 million eggs. Spawning seems to take place generally towards the evening. Stages of embryonic development up to the time of hatching are figured and described. At a water temperature of about 23° to 25° C, the egg hatches in about a day. The eggs hatch out just as well in 1% normal salt solution and in ordinary chlorinated tap water as in the river water. The newly hatched larva is 2·3 mm. long. The larvæ lived under laboratory conditions for a maximum period of 5 days attaining a length of 5·6 mm. Yolk is completely absorbed when it is about 8 mm. long. The larval development of the fish till it becomes a juvenile is described and figured. From available records it appears that growth during the first year is roughly at the rate of an inch per month. Our observations show that the fish descend into the sea during the first year of their life. The need for further study on the bionomics of the fish is indicated. The great damage done to theHilsa fishery by the capture of the countless fry and fringerlings of the fish in the tidal areas is stressed and the urgent need for the protection of the fry and the early stages is emphasized. The desirability for a proper survey of the spawning grounds in the rivers and further investigations into the fate of the egg and the larvæ that drift down the estuary is indicated.
pp 124-125 March 1951
pp 126-134 March 1951
The following general conclusions can be drawn on the seasonal variations in the chemical composition of mackerels:—
The weight of fish varies directly as length.
The tendency of ash and protein content of mackerel is to remain constant.
Water and fat are the components of fish which are subject to seasonal variation and have a reciprocal relationship.
The fat contents in mackerel rise to a maximum between September to November and fall thereafter gradually.
The average composition as revealed by analysis in the years 1947 to 1949 is shown below:— Water 73·45% Protein 20·95% Fat 3·29% Ash 1·66%
pp 135-148 March 1951
pp 148-149 March 1951
pp 150-158 March 1951
Comparison of the biological value obtained by animal experiments and the quality index of the protein obtained by chemical methods does show some parallelism between the two, How far it would be applicable in general for the determination of the nutritive value of the proteins is difficult to see at the moment. This aspect has been investigated from the point of view of cattle and poultry feeding and deserves further investigation from the standpoint of human nutrition.
Germination appears to improve the digestibility coefficient of proteins in pulses, and the availability of vitamin (unpublished work), though there is a lowering of the biological value. Hence the use of germinated pulses in food dishes.
Cotton seed contains good quality of protein and its nutritive value is also comparable with that of commonly used foodstuffs. It however contains a substance of poisonous nature (gossypol), and if it is removed cotton seed proteins can be used to supplement protein requirements of man.
pp 159-164 March 1951
Details are given of a simple method for the preparation of asparagine by alcoholic diffusion of intact seedlings of Bengal gram (Cicer arietinum). The superiority of the diffusion method as compared with the usual aqueous extraction of macerated seedlings is indicated.