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Rh of normal salt solution they must take the blood not merely from one of the same species, family and sex, but of a similar degree of masculinity or femininity.

Experiments on transfusion not only lend support to my belief in the existence of sex characters in the blood corpuscles, but they furnish additional explanations of the failure of experiments in grafting ovaries or testis on individuals of the opposite sex. The internal secretions of the genital glands are operative only in their appropriate environment of arrhenoplasm or thelyplasm.

In this connection, I may say a word as to the curative value of organotherapy. Although, as I have shown to be the case, the transplantation of freshly extirpated genital glands into subjects of the opposite sex has no effect, it does not follow that the injection of the ovarian secretion into the blood of a male might not have a most injurious effect. On the other hand, the principle of organotherapy has been opposed on the ground that organic preparations procured from non-allied species could not possibly be expected to yield good results. It is more than likely that the medical exponents of organotherapy have lost many valuable discoveries in healing because of their neglect of the biological theory of idioplasm.

The theory of an idioplasm, the presence of which gives the specific race characters to those tissues and cells which have lost the reproductive faculty, is by no means generally accepted. But at the least all must admit that the race characters are collected in the genital glands, and that if experiments with extracts from these are to provide more than a good tonic, the nearest possible relationship between the animals experimented upon must be observed. Parallel experiments might be made as to the effect of transplantation of the genital glands and injections of their extracts on two castrated cocks of the same strain. For instance, the effects of the transplantation of the testes of one of them into any other part of its own body or peritoneal cavity or into any similar part of the other cock might be compared with the effects of intravenous injection of testis extract of the one on