314 MISCELLANEOUS OBJECTIONS TO THE [Chap. VII. 



probable that such great and abrupt variations have often 

 occurred under nature, as are known occasionally to arise 

 under domestication. Of these latter variations several 

 may be attributed to reversion ; and the characters which 

 thus reappear were, it is probable, in many cases at first 

 gained in a gradual manner. A still greater number 

 must be called monstrosities, such as six-fingered men, 

 porcupine men, Ancon sheep, Xiata cattle, &c. ; and as 

 they are widely different in character from natural species, 

 they throw very little light on our subject. Excluding 

 such cases of abrupt variations, the few which remain 

 would at best constitute, if found in a state of nature, 

 doubtful species, closely related to their parental types. 

 My reasons for doubting whether natural species have 

 changed as abruptly as have occasionally domestic races, 

 and for entirely disbelieving that they have changed in 

 the wonderful manner indicated by Mr. Mivart, are as 

 follows. According to our experience, abrupt and 

 strongly marked variations occur in our domesticated 

 productions, singly and at rather long intervals of time. 

 If such occurred under nature, they would be liable, as 

 formerly explained, to be lost by accidental causes of 

 destruction and by subsequent inter-crossing; and so 

 it is known to be under domestication, unless abrupt 

 variations of this kind are specially preserved and 

 separated by the care of man. Hence in order that a 

 new species should suddenly appear in the manner 

 supposed by Mr. Mivart, it is almost necessary to 

 believe, in opposition to all analogy, that several 

 wonderfully changed individuals appeared simultane- 

 ously within the same district. This difficulty, as in 

 the case of unconscious selection by man, is avoided on 

 the theory of gradual evolution, through the preservation 



