Is the Manoilov Reaction a Better Test for Metabolic Level Than for Sex?

Abstract

In preliminary work with the Manoilov sex test we noted that a wrong or “reversed” reaction was rather frequently obtained when the test was applied to two blood samples from an adult pair of reproducing pigeons. These reversals then seemed to occur more frequently in those pairs which were incubating eggs at the time the test was made, and it was therefore decided to make a special study of the conditions attending these reversals. We designate as “reversals” those cases in which the comparison of the bloods from the two donor birds indicated the opposite of their actual sex. Conducting the study along these lines, in an animal in which many important details of the current reproductive states and processes are easily known, we have obtained results which we conclude are a contribution not only to this little understood reaction, but to the general problem of the nature of sexual difference.

When male and female mates are studied at a “resting stage” of the reproductive cycle (when no eggs are about to be laid, and when the pair is not incubating eggs) the Manoilov test gives a correct indication of the sex of the two donor birds in about 85 per cent of the tests (table 1). If, however, the blood be taken from the birds at or near the time eggs are ready to be released from the ovary, only 29 per cent of the tests give a correct answer. Also, while the birds are incubating eggs 2 to 12 days only 35 per cent of males and females are correctly placed by the test. Thus, under these two conditions, more males are diagnosed as females than as males, and vice versa.