THE STATUS OF MAN. 255 



a little twisted taU like a pig and long hanging ears, or a black 

 and white spotted Chow,-or a silver-spangled Leghorn, or a Fan- 

 tail-pigeon with feathered legs, but he will certainly expect to 

 see such combinations at the next show. Somebody who knows 

 dogs or poultry, will always classify a number of animals into 

 members of a few species, plus a number of animals of apparent 

 hybrid origin. The variability in a given group of dogs is not 

 actually smaller than it appears to be to the Zoologist, who 

 does not know the species, but there is vastly more order in it 

 than he would suppose. 



The difference between a red and a black Cocker-spaniel may 

 appear to the visiting Zoologist to be of the same order as that 

 between the red colour of a Cocker, the black and tan of a 

 spaniel, but to the dog-fancier it is quite another difference. 



It is quite impossible to understand the situation and rightly 

 to valuate the variabiUty of the domestic dog, of the domestic 

 poultry, imless one first understands the fact, that numerous 

 different species exist. And it is impossible to understand the 

 workings of selection in the amelioration of domestic animals 

 unless it is realized, that it is these species which are impro- 

 ved, and not higher units, such as populations of dogs, or all the 

 poultry of one country. 



The selection of domestic animals has served several authors 

 as a model in speculations upon the improvement of mankind 

 by encouraging desirable parents and restraining undesirable 

 ones. 



There is no doubt whatever, that in a group of animals with 

 a sufficiently high variabihty, selection in the way in which it 

 is practiced here, that is, by allowing only the occasional ani- 

 mal of exceptional merit, or at least only the occasional male, 

 to participate in reproduction, will bring about a speedy change 

 in the desired direction. 



But one or two things have to be remembered. This improve- 

 ment of a domestic species by selection can be copied from 

 one variable species to another, but a combination of species, 

 a group of higher order can not be improved by selection in 



