Excerpt from The Journal of Experimental Zoology, Vol. 27: 1918-1919 While the sex ratios for the inbred litters of the eighth to the twenty-fifth generations varied considerably, the variation was much less after the twelfth generation than before (table A part of this variation was doubtless phenotypic, Since seasonal changes in temperature seem to alter the sex ratio in the rat (king and Stotsenburg, and probably also other agencies, such as the age of the mother (king, '16 a), have a similar effect. As all of the sex ratios were relatively high, however, the devia tions from the norm cannot be ascribed either to environment or to chance, so they must have been due, in part at least, to the manner in which the breeding animals were selected. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.