INTEGUMENTARY SYSTEM 103 



mentioned the "swimming membrane," that web or skin ex- 

 tending between the fingers and linking them together. As 

 we have seen above, in the hand of the gorilla the fingers are 

 webbed as far as the middle of the first phalanx, and between 

 the third and fourth fingers the skin extends almost to the 

 second phalanx ; similarly in the chimpanzee all the fingers 

 with the exception of the thumb are connected by a membrane 

 extending to the joints between the first and second phalanx. 

 Cases of excessive growth of this membrane in man are very 

 rare. The normal web-like skin between the fingers can best 

 be observed by viewing the back of the hand with extended 

 fingers. 



Griming has measured the extent of the membrane between 

 the fingers, and found, in the case of the index finger, the length 

 of the free finger to be 6 mm. less than that of the entire finger, 

 and the second finger at the second division 21 mm. ; in most 

 cases the third finger proved to be on an average 4 mm. 1 

 longer at the second division than at the third. 



The pigmentation of the skin cannot rank as a distinctive 

 character of man in contrast to the lower animals, particularly 

 to the mammals, for the same brown colouring matter, differing 

 quantitatively, is found in the rete Malpighi, and in the uvea 

 and posterior surface of the iris in all mammals, and among all 

 the peoples of the earth. By far the greater number of human 

 beings are brunette, or darker. Red-haired people and red- 

 skinned, or copper-coloured, races have a special deposit of 

 red pigment in the hair and in the rete Malpighi. The Albinos, 

 human and animal, are the only instances of complete absence 

 of pigment ; this peculiarity is frequently inherited. The 

 members of the so-called white races possess in reality, under 

 the epidermis, a supply of darker, or lighter brown pigment 

 which appears, varying in intensity, in certain parts of the 

 body (axillae, genitals, plica ani). 



Klaatsch assumes the colouring of the oldest races to have 

 been intermediate between the present extremes, and proceeds 

 to discuss the probable causes which may have led to the 

 decrease of pigment in the white races, and thinks it to have 

 been frequently brought about by the same agencies. The 



1 Ranke, loc. cit., ii., p. 53. 



