218 DEGENERATION SEC. 



by their crossing. This instance of the " formation of new 

 species by crossing " shows that new forms may actually arise 

 by sexual mixture, and it is well known that crossing, infusion 

 of new blood, generally conduces to the vigour of the race. 

 But in unrestricted nature crossing cannot evidently have 

 such an important influence in the modification of forms. I 

 mean, that if the importance of crossing were so great, then 

 the differences between the members of a nation in different 

 districts would necessarily be much greater than it actually 

 is. For it is known that mixture among much the greater 

 part of a nation (the population of a country) takes place only 

 within quite narrow limits. In mountainous regions inter- 

 breeding is, as I have said, naturally much closer than in 

 the level country. In the former, in secluded valleys, it is 

 true, strikingly peculiar types occur, since in them remnants 

 of an older period maintain themselves with very little inter- 

 mixture ; I will mention only the dark small (in many respects 

 also degenerate) men in the valleys of the Baden Black Forest, 

 who are probably remnants of the Celts who retired to those 

 corners before the German invasion and there remained. But 

 even in level regions, considering the obstacles to intercourse 

 interposed by rivers, etc., distinct types of people would be 

 produced by the natural limitation of intercourse to a greater 

 extent than is actually the case. The natural conditions of 

 intercourse are such that thousands of such varieties would 

 have been formed in a relatively small area, each with a 

 central point where the peculiar character was most pro- 

 nounced. But simple calculation shows that perfect mingling, 

 even within a small area, requires a very long time. In order 

 that 500 people of each sex should each pair once together, 

 250,000 unions are necessary. What movements of popula- 

 tion, not to mention time, would be required before fifty or 

 sixty millions of Germans were mingled together? But 

 since, as a matter of fact, mingling occurs only within each 



