The Growth of Fish

Abstract

ABSTRACT In most studies of post-embryonic growth it is customary to accept the observed increment in the total mass of the organism per unit time as an index of growth. Davenport (1897) found, however, that the opening phases of development of the frog were characterised by a very rapid rise in the water content of the embryo whilst the dry weight during this period gradually decreased. He concluded from these facts that the process of early embryonic growth was of a different and more “passive” nature than the more “active” growth which later ensues. Passive growth was regarded by him and by others as some form of imbibition, whilst the subsequent “active” growth involved the conversion of organic substances into living tissue and so involved an increase in dry weight. In the case of terrestrial animals, however, it has been known for some time that with increasing age the percentage of water in the organism falls, and the recent figures of Murray (1926) show that this fall is detectable at a very early age. It must be remembered that Davenport’s figures apply to the whole larva which in its early stages is heavily charged with yolk, whereas Murray’s figures apply to the embryo alone.