314 STUDIES IN THE EVOLUTION OF ANIMALS 



says : ' A case of polydactylism in the Horse, or of double uterus 

 in a Woman, or of prolongation of the tail in Man, must be con- 

 sidered as a simple return to an ancestral type, that, is rever- 

 sions — anomalies, as far as the individual case is concerned, but 

 not concerning the species to which it belongs (!) ' 



One would like to ask — ^Is there any law which limits re- 

 versions ? If a polydactyl foot in a Horse is a reversion to the 

 pentadactyl foot of some ancestral form, why is not sex-digita- 

 tion in Man a reversion to something like the octodactyl hand 

 of the Ichthyosaur? 



M. Guinard appears to me to lay too much stress on what he calls 

 specific type, as if there were any truth in the antiquated dogma that 

 specific types are unchangeable and are not modifications of some 

 other pre-existing types. If supernumerary mammae in a Woman, 

 and horns in a Horse, are reversions to conditions existing in other 

 species, it appears to me that there is no good reason for supposing 

 that reversions can go, not only beyond the species, but beyond 

 the genus, and the order too, for it seems to me that artificial sub- 

 divisions in the flow of what we call ' vital energy ' are as artificial 

 as a classification of the different portions of a waterfall would be ! 



Dr. Wallace, in Darzvinism, ^. loi, says: 'On comparing the 

 variations which occur in one generation of domestic animals with 

 those which we know to occur in wild animals, we find no evidence 

 of greater individual variation in the former than in the latter.' 



I suppose by variation he means the ordinary small variations 

 which are peculiar to every individual ; for on p. loo he refers to 

 monstrosities only with reference to artificial accumulations of 

 something beautifully novel, strange, or amusing. Some of these 

 artificial monstrosities would be injurious, such as the tumbling of 

 Pigeons. In his work on Darwinism I cannot find that Dr. 

 Wallace even suspected that a new type of animal or plant might 



