GENERAL PRINCIPLES OF BREEDING. 11 



founded on pure assumption and supported by no clear proof. 

 The gradual extinction of the influence of the first male in 

 successive pregnancies by other males is what would scarcely 

 be expected if the blood was charged with gemmules from 

 the first capable of reproducing themselves and especially 

 prone to rapid increase and development in connection with 

 the development of offspring. Again, similar elements must 

 be introduced into the maternal blood when the vital fluid 

 has been transfused into her veins from those of another 

 person or of a beast, and the ovules then in course of devel- 

 opment in her ovaries must be "affected and hybridized" if 

 such blood is not exactly identical in composition with her 

 own. But though transfusion of blood into the female sys- 

 tem is not uncommon, and though that blood has been re- 

 reatedly taken from a person of a widely different race, no 

 complaint has ever been made that the children have been 

 thereby affected. 



A more satisfactory explanation is that advanced by the 

 present writer, in a paper read in 1875 before the American 

 Public Health Association: "It is a well-known pathologi- 

 cal fact that adjacent cells tend to engraft their plastic or 

 formative powers upon each other. I prick my skin with a 

 needle; immediately the injured cells and nuclei undergo a 

 rapid increase in size and numbers. But the effect does not 

 end there; those adjacent take on a similar action, and the 

 extent of the resulting inflammation is only limited by that 

 of the injury and the susceptibility of the parts. Again, in 

 placing a slice of scarf skin in the middle of a raw sore we 

 inoculate the cells of the adjoining granulations and em- 

 power them to develop scarf skin. How, then, can we avoid 

 the conclusion that the impregnated ovum impresses its own 

 characters on the mass of the decidua, and through this on 

 the maternal mucous membrane, and that this in its turn 

 impresses its characters on the membrane and embryo of 

 the next succeeding conception?" 



It has been opposed to the theory of contamination of the 

 mother's blood, that in the case of woman the father of the 

 first child rarely affects the appearance of those by other 

 fathers. Mr. Allen has known instances in which white 



