ABSTRACT
Several years ago Reach (1912) made comparisons of the amount of calcium that could be recovered from ashing of the entire bodies of male and female white mice. He worked with normal and gonadectomised males and females and obtained higher percentages of CaO from both groups of females (1·283 normal, 1·275 ovariotomised), and lower percentages from both groups of males (1·180 and 1·005). Reach accordingly arrived at the conclusion that “here we have a secondary sexual character—the ♀♀ of these animals are richer in Ca than the ♂♂.” More recently Hammett (1923) working on the femur and humerus of rats earlier thyro-parathyroidectomised at a hundred days found the amount of Ca in the males unchanged but slightly less than normal in the females, thereby suggesting some difference in the calcium metabolism of the sexes. Riddle and Honeywell (1925) undertook the study of calcium metabolism in relation to sex in the pigeon. They worked on blood serum, employing the method of Kramer and Tisdall (1921), and obtained two determinations from each bird at intervals of ten days. They obtained a sex-dimorphism, the males as a group showing a lower and the females a higher Ca content. They state, however, that only on a basis of sex had they found a consistent grouping of values.
