86 PHYSIOLOGY. 



tion of the atmosphere, it is not carried off as fast as formed, it ac- 

 cumulates upon the surface, constituting the sensible perspiration. 

 It has usually an acid reaction, which is due to the presence either 

 of acetic or lactic acid. It contains also a small amount of animal 

 matter, and some salts, principally chlorides. 



The entire amount of fluid insensibly lost from the cutaneous and 

 pulmonary surface is estimated at 18 grs. per minute ; of these 11 

 pass off by the skin, the remainder by the lungs. The maximum 

 loss from both sources during 24 hours is equal to about 5 lbs., the 

 minimum 1§ lb. 



The perspiratory secretion is depuratory and vicarious with that 

 of the kidney, both separating the superfluous azotized matters. 

 The amount of solid matter thrown off from the skin in 24 hours is 

 about 100 grains. The amount of fluid thrown off is influenced 

 greatly by external temperature, being greatest when it is elevated, 

 the object of which increase is to keep down the temperature of the 

 body by evaparation. It is also influenced by general conditions of 

 the vascular and nervous system, though the manner is not yet well 

 understood. 



A peculiar glandule, resembling the sudoriferous, but larger, has 

 lately been described as existing in fRe axillse ; these are called the 

 odoriferous or miliary^ and probably serve to secrete the character- 

 istic odour of those parts. The odorous principle may be detected 

 in blood which has been dried, by treating it with sulphuric acid : 

 and it is said to differ so much in di^erent animals as to afford a test 

 by which their blood can be recogniS?i3. It has even been said that 

 the blood of the female can by this means be distinguished from that 

 of the male. 



GLANDULAR SECRETIONS. 



The lachrymal secretion is formed by the gland of that name, 

 whose seat and structure are described in the anatomical division. 

 It is one of the granular glands, and pours its secretion upon the 

 surface of the conjunctiva to cleanse and lubricate. The lachrymal 

 fluid resembles dilute serum deprived of a great part of its albumen. 

 It is a constant secretion, and is absorbed by the open orifices of the 

 nasal ducts, and carried into the nose as fast as it is poured out. 

 The cause of this absorption is probably capillary attraction, assisted 

 by the syphon-like action of the nasal duct. This secretion is greatly 

 influenced by the emotions. 



The salivary secretion is formed by the Parotids^ Submaxillaries, 

 Suhlinguals, and Pancreas, the latter is sometimes called the ab- 

 dominal salivary gland. These glands also come under the division 

 of the granular glands, being composed of aggregated follicles, dis- 

 charging into an excretory duct. 



