70 A TREATISE ON HORSE-BREEDING. 



lungs to the young animal. But we have no proof of living 

 particles from the blood of the foetus entering into the cir- 

 culation of the mother, unless we accept as such the very 

 phenomenon we are endeavoring to find an explanation for: 

 and this would only be admissible if no other or more reason- 

 able explanation could be found. 



A slight modification of McGillivray' theory is that of 

 Darwin, advanced in his doctrine of pangenesis. He teaches 

 that throughout the blood and system of every animal there 

 are living particles, infinitesimally minute, but with certain 

 plastic or formative powers, by virtue of which they can 

 build up particular forms or produce peculiar characteristics 

 in the animal economy. That such particles may remain 

 dormant for months or years, or even for a number of suc- 

 cessive generations of animals, being, meanwhile, transmitted 

 from parent to offspring through the microscopic ovum and 

 spermatozoon, and will only be roused to activity and growth 

 and build up the forms and beings, like those from which 

 they were derived, when there occurs a change of circum- 

 stances favorable to their development. By this means he 

 explains many cases of apparent "sports," or variations from 

 the type of the known ancestors; many sudden advances in 

 excellence,, and retrogressions. 



As applied to the phenomenon under consideration it is 

 taught that these infinitesimal particles (gemmules), passing 

 through the membranes from the blood of the foetus into that 

 of the mother, circulate with it, affecting the ovarium of the 

 female, so that the ovules and offspring subsequently pro- 

 duced by her when impregnated by other males are plainly 

 affected and hybridized by the first male. 



It will be readily conceded that such particles circulating 

 in the blood of the mother will be much less likely to affect 

 her own system, already matured, insusceptible and under- 

 going the changes of nutrition only, than the growing ele- 

 ments of the ovum or the tissues of the embryo in active 

 process of growth, and with a power of development equal in 

 some cases to the reproduction of an organ accidentally lost. 

 Much, indeed, might be said in favor of the theory; yet, as 

 in its less elaborate. form propounded by McGillivray, it is 



