200 THE HUMAN SPECIES 



sweat-glands of the face, buttocks and extremities ; l Foster, 

 however, attributed the activity of the sweat-glands to vaso- 

 motor changes alone. 



The exact amount of sweat secreted daily cannot be exactly 

 determined on account of the numerous influences to which 

 it is subject, especially as without the appearance of sweat 

 a considerable amount of water is excreted by the skin in 

 transpiration. Moreover, it must be remembered that both in 

 man and animals a certain antagonism exists between kidney 

 and skin excretion. 



For instance, in man, after excessive muscular exertion the 

 urine is diminished while the sweat is increased, and the urea 

 present in the latter is relatively rVirr that of the urine 

 (Argutinsky). 2 



In addition to a varying water-content, the sweat contains 

 certain inorganic constituents, sodium chloride, phosphates of the 

 alkaline earths and iron oxide ; while its organic constituents 

 besides urea are fluid fatty acids, cholesterin, neutral fat and 

 albumin. 



As specific constituents of human sweat there occur also 

 creatinin, aromatic oxides, aethereal sulphates of phenol and 

 skatoxyl, together with occasional variable amounts of an acid 

 whose composition is represented by the formula C 10 H 16 N 3 O 13 . 

 To which of these constituents is to be attributed the toxicity of 

 human sweat described by Arloing requires further investigation. 



The secretion of fat by the skin, which in many animals, 

 especially sheep, acts as a means of lubricating the skin and 

 fleece as well as a protection against the wet, plays in man 

 generally a small part, and no definite estimations of its amount 

 have been made. [-Rosenfeld 3 states that the total fat excreted 

 by the skin of a healthy European adult varies from i to 2*5 

 gm. per diem : ordinary exercise does not affect the excretion, 

 but the amount of fat is considerably diminished if carbohyd- 

 rates are withheld from the diet.] The amount varies not 

 merely in individual but in races, being greatest in negroes 

 whose sebaceous glands are so active that their skin is quite 

 soft and greasy to the touch. The characteristic odour which 



l Munk-Schultz, loc. cit., p. 528. 2 Ibid., p. 262. 



3 Rosenfeld, Zentralbl.f. innere Med., 1906, xxvii., 986. 



