Volume 15, Issue 1
January 1942, pages 1-74
pp 1-42 January 1942
The rate of growth and period of breeding of the following sedentary organisms in the Madras Harbour have been worked out:—Laomedea (Obella)spinulosa, Hydroides norvegica, Crisia sp.,Membranipora sp. (growth alone),Ostrea madrasensis, Mytilus viridis, Patella (Cellana)cernica (breeding alone),Balanus amphitrite, Polycarpa sp., andDiandrocarpa brackenhielmi.
The environment and the methods employed in this study are described.
The rates of growth of the different forms studied, have been compared with those of corresponding or related forms in different parts of the world.
The species investigated attain their sexual maturity very early in their life.
There seems to be continuous growth throughout the year.
Reference is made to the breeding of other tropical marine animals and it is found that breeding takes place:—(a) once a year, not lasting the whole year round, (b) twice a year, with a quiescent phase between the two periods, (c) continuously but with an intensity during a certain portion of the year, (d) continuously without any marked intensity and (e) discontinuously depending on the phases of the moon.
The influence of temperature on breeding in marine animals in the tropics is discussed and it is inferred that temperature is not the only factor influencing breeding.
pp 43-57 January 1942
pp 58-60 January 1942
pp 61-74 January 1942
Two species of a localDatura were crossed and the hybrid compared with the parents.
The somatic chromosome complements of the parents were analysed and compared with that of the hybrid.
Meiosis in the parents and the hybrid is also described. Chromosomal pairing in the hybrid is discussed as throwing light upon the relationship between the parents.