Reproduction and Heredity

Abstract

PROF. J. A. DETLEFSEN (University of Illinois) has made an important contribution to our knowledge of “Mendelian” inheritance by his “Genetic Studies on a Cavy Species Cross” (Carnegie Institution, Publication No. 205, 1914). The research begun by Prof. W. E. Castle—is of interest as affording information from the crossing of two distinct species, for the wild Brazilian cavy (Cavia rufescens) is apparently sharply distinct from the common domestic guinea-pig (C. porcellus). The sterility of hybrid animals is known to be a rule admitting of many exceptions. In the experiments with cavies here described, crosses between C. rufescens males and C. porcellus females gave completely sterile male and fertile female hybrids. By mating the female hybrids with porcellus males, quarter-wild hybrids were obtained, again sterile males and fertile females; but by repeated back-crosses of female hybrids to porcellus males, individuals with increasing fertility were obtained. “Fertility seemed to act like a very complex recessive character; for the results obtained were what one would expect if a number of dominant factors for sterility were involved, the elimination of which would give a recessive fertile type.” The paper is noteworthy because skeletal characters of the parents and hybrids are figured and compared, in addition to the usual external features, such as coat-colour.