798 THE SKIN AND ITS SECRETIONS. 



The Perspiration. Of the secretions of the skin, whose quantity 

 amounts to about -^ of the weight of the body, a disproportionately 

 large part consists of water. Next to the kidneys, the skin, in man, is 

 the most important means for the elimination of water. As the glands 

 of the skin and the kidneys stand near to each other in regard to their 

 functions, they may to a certain extent act vicariously. 



The circumstances which influence the secretion of perspiration are 

 numerous, and the quantity of sweat secreted must consequently vary 

 considerably. The secretion differs in different parts of the skin, and 

 it has been stated that the perspiration of the cheek, that of the palm 

 of the hand, and that under the arm stand to each other as 100:90:45. 

 From the unequal secretion on different parts of the body it follows that 

 no results as to the quantity of secretion for the entire surface of the 

 body can be calculated from the quantity secreted by a small part of the 

 skin in a given time. In determining the total quantity a stronger 

 secretion is as a rule produced, and as the glands can with difficulty 

 work for a long time with the same energy, it is hardly correct to estimate 

 the quantity of secretion per day from a strong secretion during only 

 a short time. 



The perspiration obtained for investigation is never quite pure, but 

 contains cast-off epidermis-cells, also cells and fat-globules from the 

 sebaceous glands. Filtered perspiration is a clear, colorless fluid with 

 a salty taste and of different odors from different parts of the body. The 

 physiological reaction is acid, according to most reports. Under certain 

 conditions an alkaline sweat may be secreted (TRUMPY and LUCHSINGER, 

 HEUSS). An alkaline reaction may also depend on a decomposition 

 with the formation of ammonia. According to a few investigators the 

 physiological reaction is alkaline, and an acid reaction depends, upon 

 an admixture of fatty acids from the sebum. CAMERER found that 

 the reaction of human perspiration in certain cases was acid and in 

 others alkaline. MORIGGIA found that the sweat from herbivora was 

 ordinarily alkaline, while that from carnivora was generally acid. 

 SMITH 1 showed that horse's sweat is strongly alkaline. 



The specific gravity of human perspiration varies between 1.001 

 and 1.010. It contains 977.4-995.6 p. m., average about 982 p. nu 

 water. The solids are 4.4-22.6 p. m. The molecular concenti ation 

 also varies widely and the freezing-point depression depends essentially 

 upon the content of NaCl. ARDIN-DELTEIL found J= 0.08-0.46, 

 average-0.237. BRIEGER and DISSELHORST found with perspiration 



1 Triimpy and Luchsinger, Pfliiger's Arch., 18; Heuss, Maly's Jahresber., 22; Cam- 

 erer, Zeitschr. f. Biologic, 41; Moriggia, Moleschott's Untersuch. zur Naturlehre, 11; 

 Smith, Journ. of Physiol., 11. In regard to the older literature on perspiration, see 

 Hermann's Handbuch, 5, Thl. 1, 421 and 543. 



