Recent Marine Biology

Abstract

THE December issue of the Journal of the Marine Biological Association contains several papers of exceptional interest. One of these, by Dr. Allen and Mr. Sexton, gives a detailed account of experiments with reference to the inheritance of eye-colour in Amphipods, and in a further paper Dr. Allen presents the general results in a very attractive manner. Gam-marus chevreuxi had been maintained in the laboratory aquaria for several years, and, quite suddenly, in the third generation of a family of these animals, a striking mutation occurred. Normally the eye possesses black pigment, beneath which is chalk-white matter, but in some individuals of this family the black was replaced by red. A pure black-eyed stock which bred true for three years was mated with a red-eyed stock, which again bred true for five generations. Black behaved as dominant, and red as recessive, and the results of further breeding were in very close correspondence with Mendelian theory. Thus black hybrids carrying red were mated together, giving 4393 offspring, and 3327 of these were black and 1066 red. (The expected results are 3294 and 1098). In the course of the experiments a second mutant appeared in which there was neither black nor red pigment in the eye, but only the deeper-lying chalk-white matter. This albino condition was also transmitted in very close correspondence with expected Mendelian results. Yet a third mutant was observed, a condition in which the chalk-white pigment was absent, and this “no-white” variety behaved as a recessive to dominant white and also closely followed Mendelian laws of numbers. Thus there was a gradual loss of factors, and accompanying the process of albinism there was degeneration of the ommatidia of the eye, a tendency towards the production of such a condition as that exhibited by the various blind species of subterranean Amphipods.