238 MiaGELLANEOUa OBJECTIONS TO TBE 



ing at once." For instance, he supposes that the differ- 

 ences between the extinct three-toed Hipparion and the 

 horse arose suddenly. He thinks it difficult to believe that 

 the wing of a bird "was developed in any other way than 

 by a comparatively sudden modification of a marked and 

 important kind ;" and apparently he would extend the 

 same view to the wings of bats and pterodactyles. _ Tliis 

 conclusion, which implies great breaks or discontinuity in 

 the series, appears to me improbable in the highest degree. 



Every one who believes in slow and gradual evolution, 

 will of course admit that specific changes may have been 

 as abrupt and as great as any single variation which we 

 meet with under nature, or even under domestication. 

 But as species are more variable when domesticated or cul- 

 tivated than under their natural conditions, it is not prob- 

 able 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, Niata cattle, etc.; 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 subse- 

 quent intercrossing; and so it is known to be under do- 

 mestication, unless abrupt variations of this kind are spec- 

 ially 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 



