Blood calcium in relation to sex in pigeons

Some years ago Reach1 made comparisons of the amount of calcium recoverable from ashing the entire bodies of male and female white mice. His examination included fair numbers of normal males and females, and of other males and females which had been castrated 42-108 days. He obtained higher percentages of CaO from both groups of females (1.283 normal; 1.275 castrated) and lower percentages from the two groups of males (1.180 and 1.005). Regarding the utilization of calcium, Reach drew the conclusion that “we have here a secondary sexual character —the females of these animals are richer in calcium than the males.” Lawrence and Riddle2 later showed that there is more phosphorus in the blood serum of female than of male fowls; and that still larger amounts of phosphorus are found in the blood of the laying hens than of non-laying hens. In view of the known relationships of the calcium and phosphorus of the blood, both of the preceding studies suggest that the sexes—at least in birds—may show differences in their calcium metabolism. Because of its bearing on the problem of sexuality in pigeons the present study was undertaken. Present methods of blood calcium determination probably warrant the assumption that a sufficient number of determinations made on normal carefully controlled birds will reveal differences, if any very notable sexual differences exist. This report, however, does not represent an adequate study; it deals with the data obtained in a first attack on the problem. The Kramer and Tisdall method was used. Our determinations therefore are for calcium plus appreciable but unknown amounts of magnesium. Along with each serum sample a check determination was made on oxalate solution of known strength. Adult birds of three kinds were taken for study; most of the pairs (except “family hybrids”) were in a more or less active state of reproduction. The age and the obvious reproductive history of all birds were exactly known. All birds-at least the male and female of each pair studied-had been subject to closely similar conditions of diet, light, confinement and parentage. Some of the birds proved at autopsy to be infested with intestinal worms (Ascahdia) or were otherwise not entirely healthy. The members of a pair were usually not of identical age