V.] SPECIFIC STABILITY. 133 



osition here maintained, inasmuch as he distinctly affirms 

 the existence of a marked internal barrier to change in cer- 

 tain cases. And if this is admitted in one case, the prin- 

 ciple is conceded, and it immediately becomes probable 

 that such internal barriers exist in all, although enclosing 

 a much larger field for variation in some cases than in 

 others. Mr. Darwin abundantly demonstrates the variabil- 

 ity of dogs, horses, fowls, and pigeons, but he none the less 

 shows clearly the very small extent to which the goose, the 

 peacock, and the guinea-fowl have varied. 7 Mr. Darwin at- 

 tempts to explain this fact as regards the goose by the ani- 

 mal being valued only for food and feathers, and from no 

 pleasure having been felt in it on other accounts. He adds, 

 however, at the end the striking remark, 8 which concedes 

 the whole position, " but the goose seems to have a sin- 

 gularly inflexible organization" This is not the only 

 place in which such expressions are used. He elsewhere 

 makes use of phrases which quite harmonize with the con- 

 ception of a normal specific constancy, but varying greatly 

 and suddenly at intervals. Thus he speaks ' of a whole 

 organization seeming to have become plastic, and tending 

 to depart from the parental type. That different organ- 

 isms should have different degrees of variability, is only 

 what might have been expected a priori from the exist- 

 ence of parallel differences in inorganic species, some of 

 these having but a single form, and others being poly- 

 morphic. 



To return to the goose, however, it may be remarked 

 that it is at least as probable that its fixity of character is 

 the cause of the neglect, as the reverse. It is by no means 

 unfair to assume that had the goose shown a tendency to 

 vary similar in degree to the tendency to variation of the 



7 " Animals and Plants under Domestication," vol. L, pp. 289-295. 



8 " Origin of Species," 5th edit., 1869, p. 45. 



9 Ibid., p. 13. 



