INTEGUMENTARY SYSTEM 201 



distinguishes man from animals, race from race, and even 

 individuals of the same nationality one from another, depends 

 upon variations in the fat and sweat secreted by the skin. It 

 is remarkable that just as the European finds the odour of the 

 African negro most unpleasant, so does the Japanese complain 

 of the smell peculiar to European skins. 



It has been well known for many years that the odour of the 

 skin depends on altered fats, albuminates and lecithin which 

 enter the blood in gaseous condition and are excreted again 

 with the sweat and sebum. Gustav Jager l has minutely studied 

 this subject, and it forms the basis of his claims to have dis- 

 covered the " soul," which he regards as the exhalations peculiar 

 to every animal as well as man. The soul he believes to reside 

 in the combined albumin molecule which is liberated upon the 

 decomposition of the albumen, so that the exhaled substances 

 consist of the soul itself even though the soul is in a condition 

 of disintegration. 



There are no data as to the extent of the daily desquama- 

 tion of epidermis and shedding of hair and nails in man. [Von 

 Noorden estimates the amount in terms of nitrogen at 1-2 

 decigrammes daily.] We only know that in general these 

 keratinous structures " wear out " in animals at a varying rate 

 probably constant for the individual and that they either 

 fall off spontaneously or are rubbed off mechanically. In a 

 dog weighing thirty kilos, Voit puts the daily waste of hair 

 and skin at 1-2 gm. In oxen the daily loss of hair varies, 

 according to the season of the year, between 2 and 20 gm. ; 

 in horses the daily average is 5-6 gm. 



There is a difference between man and animals in that the 

 latter usually show a double growth of hair, in spring and in 

 autumn ; while in man the hair falls out and grows again fairly 

 evenly throughout the year. A certain seasonal influence can 

 however be traced, for in spring and summer the rate of growth 

 is 27 per cent, more than in autumn and winter. 



The daily formation of keratin in the hair of the head 

 is about 40 mgm. (Beneke), that of the finger and toe-nails 

 5-9 mgm. (Moleschott). 2 



Whether the intact skin has the power of absorption has 



1 Jager, Die Entdeckung der Seele. 2 Munk-Schultz, loc. cit., p. 264. 



