PAMMIXIS 217 



importance which must be ascribed to degeneration in the 

 formation of species is shown by the most elementary know- 

 ledge of animal forms. 



PAMMIXIS 



Pammixis, it is self-evident, only affects the question of 

 the modification of species in cases of forms which are 

 confined and isolated within a comparatively narrow territory, 

 if by pammixis is meant the cessation of selection and the 

 consequent levelling sexual intercourse of all forms without 

 distinction that is, in English, in-and-in-breeding. In small 

 political districts, especially in those which are in mountain- 

 ous regions, such as are found among Germans, especially in 

 Switzerland, the effect of in-breeding must with respect to 

 human beings be particularly evident, as far as the produc- 

 tion of similarity of characters is concerned. But even here 

 the result which first appears is obviously only that one or 

 another character which has arisen from the action of some 

 external conditions on a few individuals becomes prevalent. 

 Thus in the Canton of Appenzell I noticed an extremely 

 remarkable variety of man among the male population. This 

 variety is distinguished by perfectly curly, luxuriant, reddish- 

 brown hair on the large skull. Selection, either general or 

 sexual, cannot by any means be assumed here. Eather the 

 origin of the peculiarity is due either directly to the general 

 action of external conditions, or a few ancestors have acquired 

 it as a result of such conditions, or have introduced it, and 

 impressed it on the whole population. But it follows from 

 my previous arguments that such general distribution, unless 

 favoured by external conditions, is very very gradual. 



Nageli found that when he planted numerous species of 

 Hieracium from different regions all together in the botanic 

 garden, new species with peculiar characters were produced 



