XVII THE METHOD OF ORGANIC EVOLUTION 359 



may be strangely modified in form and function, as in the 

 flappers of the whale, or in the wing of the bat, yet never 

 once in the whole long series of land-vertebrates do they 

 normally exceed five in number. Yet we have six, seven, or 

 eight-fingered, double-handed, or double-footed children ; 

 similar malformations in monkeys ; six and seven-toed 

 cats ; four, five, or six-toed pigs ; double-footed birds, and 

 other monstrosities, described at great length, and all their 

 peculiarities discussed in the most minute detail and from 

 various points of view, in a work presented to us as " a 

 contribution to the study of the -problem of species." 

 Many of these malformations have been observed among 

 animals in a state of nature, and in fact, Mr. Bateson 

 believes that they occur as frequently among wild as 

 among domesticated animals. Considering how rarely 

 the former cases can be observed, they must be every- 

 where occurring ; yet in no one single instance do they seem 

 to have established themselves as a race or local variety 

 on however small a scale. Yet we know that in the case 

 of the six-toed cats, and probably in other cases, they are 

 easily transmissible ; and we must, therefore, conclude that 

 all these irregularities and monstrosities are in a high 

 degree disadvantageous, since when subject to free compe- 

 tition with the normal form in a state of nature they 

 never survive, even for a few generations. 



Variations in Number of Serial Parts rarely a 

 Factor in Origin of SiKcies. 



As the volume we are discussing is entirely devoted to 

 variations in the number or position of the serial parts of 

 organisms in relation to the origin of species, it becomes 

 necessary to lay some stress upon the very familiar, but 

 apparently overlooked fact, that, among all the higher 

 types of life at all events, the most stable of all characters, 

 and the most permanent during long periods of evolution, 

 and throughout changes which have led to the production 

 of a marvellous variety and abundance of specific forms, 

 are these very characters of the number and relative 

 positions of serial organs ; whence it follows that variations 



