136 THE GENESIS OF SPECIES. [CHAP. 



all wild animals have a capacity for change similar to that 

 existing in some of the domestic ones. It seems more 

 reasonable to maintain the opposite, namely, that if, as 

 Mr. Darwin says, the capacity for change is different in 

 different domestic animals, it must surely be limited in 

 those domestic animals which have it least, and a fortiori 

 limited in wild animals. 



Indeed, it cannot be reasonably maintained that wild 

 species certainly vary as much as do domestic races ; it is 

 possible that they may do so, but at least this has not been 

 yet shown, Indeed, the much greater degree of variation 

 amongst domestic animals than amongst wild ones is asserted 

 over and over again by Mr. Darwin, and his assertions are 

 supported by an overwhelming mass of facts and instances. 



Of course, it may be maintained that a tendency to in- 

 definite change exists in all cases, arid that it is only the 

 circumstances and conditions of life which modify the 

 effects of this tendency to change so as to produce such 

 different results in different cases. But assertion is not 

 proof, and this assertion has not been proved. Indeed, it 

 may be equally asserted (and the statement is more conso- 

 nant with some of the facts given), that domestication in 

 certain animals induces and occasions a capacity for change 

 which is wanting in wild animals the introduction of 

 new causes occasioning new effects. For, though a certain 

 degree of variability (normally, in all probability, only 

 oscillation) exists in all organisms, yet domestic ones are 

 exposed to new and different causes of variability, resulting 

 in such striking divergencies as have been observed. Not 

 even in this latter case, however, is it necessary to believe 

 that the variability is indefinite, but only that the small 

 oscillations become in certain instances intensified into 



