374 



PHYSIOLOGY 



CHAP. 



European 



Negro 



Australian 



different sexes belonging to different races can interbreed and 

 produce hybrids or half-castes who are fertile in their turn. 

 Most biologists regarded this fact as proof positive of the affinity 

 of species ; Sergi, however, does not consider it of absolute value, 

 since Morgan has proved that the degrees of sterility and fertility 



vary enormously in the 

 different species, both vege- 

 table and animal, the pro- 

 duct of some species which 

 have been crossed being 

 sterile hybrids, whilst others 

 give rise to fruitful hybrids. 

 He further points out (bas- 

 ing his remarks on Valcker's 

 study of the crossing of 

 primitive and white races) 

 that the fertility of half- 

 breeds is relatively ex- 

 tremely limited. 



Morselli's monogenism 

 is based on the arguments 

 " that all human races show 

 characteristics of the same 

 type, more especially in 

 those structural peculiarities 

 of specific value to the 

 zoologist, such as the type 

 of the brain, the dentition 

 and the teeth, the shape 

 of the hands and feet, that 

 of the lips, the hair in the 

 armpits and on the pubis, 

 etc. Facts of importance 

 to the physiologist are, in 

 addition to the fundamental 

 fact of mutual fecundity, 

 the equality of blood, the 



Pia. 140. ^Development of the chin from the lower to . i -T, r j 



the higher types according to Gaudray. (G. Bnschan.) COmmuniCablllty OI diseases, 



the like periodicity of men- 

 struation, the same period of pregnancy, the birth of not more 

 than one child at a time as a general rule, the existence of 

 bluish marks on the skin of new-born children of distant races, 

 etc. Other witnesses to psychological unity are the marvel- 

 lous universal phenomenon of articulate language, the great 

 similarity in the method of giving expression to the emotions, 

 in intellectual conceptions and creations, the forms of social 

 organisation, and finally the proved capacity for education 



Diluvial 



Chimpanzee 



