A tremendous amount of laboratory experimentation upon animals has been done in late years to determine the nature of sex.  For example, Goodale[16] castrated a brown leghorn cockerel twenty-three days old and dropped pieces of the ovary of a female bird of the same brood and strain into the abdominal cavity.  These adhered and built up circulatory systems, as an autopsy later showed.  This cockerel, whose male sex glands had been exchanged for female ones, developed the female body, and colouration so completely that expert breeders of the strain pronounced it a female.  He found that simply removing the female sex glands invariably led to the development of spurs and male plumage.  But simple removal of the male sex glands did not alter plumage.  To make sure, he replaced the male sex glands with female, and found that the former male developed female plumage.

This obviously signifies that in birds the female is an inhibited male.[4, p.49.] Either sex when castrated has male feathers—­the male has them either with or without testes, unless they are inhibited by the presence of (transplanted) ovaries.  It will be remembered that the sociological theory of sex held by Ward, Mrs. Hartley and a host of others was founded on the supposition that evolution or development of a species is chiefly due to selection by the females of the better males, a conclusion based almost entirely on bird evidence.  Ward[17] states that “the change or progress, as it may be called, has been wholly in the male, the female remaining unchanged”; also that “the male side of nature shot up and blossomed out in an unnatural, fantastic way....”  Speaking of the highly-coloured males, especially among birds, the same writer states that “the normal colour (italics ours) is that of the young and the female, and the colour of the male is the result of his excessive variability.”  Goodale’s results completely refute this idea, and should bury for ever the well-known sociological notion of “male afflorescence.”

The general doctrine of a stable, “race-type” female and a highly variable male has been widely circulated.  In tracing it back through voluminous literature, it appears to have been founded on an article published by W.I.  Brooks in the Popular Science Monthly for June, 1879, fourteen years before Weissmann’s enunciation of the theory of continuity of the germ-plasm.  Like Wallace, Brooks continued to study and experiment till the last, and finally withdrew from his earlier position on sexual selection.  However, this has not prevented others from continuing to quote his discarded views—­innocently, of course.