THE INADEQUACY OF "NATURAL SELECTION." 167 



source repeats itself as far as possible. Hence a conflict of tend- 

 encies to evolve two structures more or less unlike. The tenden- 

 cies do not harmoniously conspire ; but produce partially incon- 

 gruous sets of organs. And evidently where the breed is one in 

 which there are united the traits of various lines of ancestry, 

 there results an organization so full of small incongruities of 

 structure and action, that it has a much-diminished power of 

 maintaining its balance ; and while it can not withstand so well 

 adverse influences, it can not so well hold its own in the offspring. 

 Concerning parents of pure and mixed breeds respectively, sev- 

 erally tending to reproduce their own structures in progeny, we 

 may, therefore, say figuratively that the house divided against 

 itself can not withstand the house, of which the members are in 

 concord. 



Now if this is shown to be the case with breeds the purest of 

 which have been adapted to their habitats and modes of life dur- 

 ing some few hundred years only, what shall we say when the 

 question is of a breed which has had a constant mode of life in 

 the same locality for ten thousand years or more, like the quagga ? 

 In this the stability of constitution must be such as no domestic 

 animal can approach. Relatively stable as may have been the 

 constitutions of Lord Morton's horses, as compared with the con- 

 stitutions of ordinary horses, yet, since Arab horses, even in their 

 native country, have probably in the course of successive con- 

 quests and migrations of tribes become more or less mixed, and 

 since they have been subject to the conditions of domestic life, 

 differing much from the conditions of their original wild life, and 

 since the English breed has undergone the perturbing effects of 

 change from the climate and food of the East to the climate and 

 food of the West, the organizations of the horse and mare in ques- 

 tion could have had nothing like that perfect balance produced in 

 the quagga by a hundred centuries of harmonious co-operation. 

 Hence the result. And hence at the same time the interpretation 

 of the fact that analogous phenomena are not perceived among 

 domestic animals, or among ourselves ; since both have relatively 

 mixed, and generally extremely mixed, constitutions, which, as we 

 see in ourselves, have been made generation after generation, not 

 by the formation of a mean between two parents, but by the jum- 

 bling of traits of the one with traits of the other, until there exist 

 no such conspiring tendencies among the parts as cause repetition 

 of combined details of structure in posterity. 



Expectation that skepticism might be felt respecting this al- 

 leged anomaly presented by the quagga-marked foal, had led me 

 to think over the matter; and I had reached this interpretation 

 before sending to the College of Surgeons Museum (being unable 

 to go myself) to obtain the particulars and refer to the records. 



