HO HUMAN PHYSIOLOGY 



The nerves of sweat secretion after leaving the cord run 

 through the sympathetic and later on join the nerves going 

 to the extremities. The center for the secretion of sweat is 

 supposed to be situated in the cord, for after the cord of a 

 cat has been cut in the cervical region, heat or dyspnoea still 

 produces sweating of the hind legs. A primary sweat 

 centre is supposed to be situated in the medulla oblongata. 

 The secretion of sweat is inaugurated by increase in tem- 

 perature, asphyxia, poisons (pilocarpin^ and also by psy- 

 chical influences (the sweat of fear). Atropin inhibits the 

 secretion. 



9. SEBACEOUS SECRETION 



The sebaceous secretion is an oily substance, consisting 

 mainly of cholesterin esters of fatty acids. Concerning its 

 composition but little is as yet known. The sebaceous 

 secretion oils the skin and hair. 



The sebaceous glands are composed of a gland body 

 which is formed by a number of saccules. The outer cells 

 of these saccules are small cuboidal cells, while the inner 

 cells are large and spherical and fill the whole saccule and, 

 by their breaking up, form the secretion. The duct leading 

 from the gland to the exterior is formed by the continuation 

 of the outer hair-follicle; it is, therefore, formed from layers 

 of pavement epithelial cells. 



Concerning the influence of the nervous system upon 

 sebaceous secretion nothing is known. 



10. LACHRYMAL SECRETION 



Tears are composed of a clear, alkaline salty fluid. They 

 contain about ifo solids, chiefly salts (NaCl). Proteids are 

 present in small quantities. 



The lachrymal glands are built like the albuminous sali- 

 vary glands. The tears are secreted continuously. Their 

 secretion is, however, under the influence of the nervous 

 system; it is increased by psychical influences (weeping), 



