372 



EXTERNAL INTEGUMENT. 



to imagine that cutaneous absorption takes place only in the 

 case of volatile matters. Rabuteau tells us that if iodine is 

 found in the urine after rubbing with an ointment containing 

 an iodide, or after wearing a shirt dipped in iodide of potas- 

 sium, it is because the acids of the fats, which at length turn 

 rancid, as well as the acids of the perspiration, have set free 

 the iodine, which, from its volatility, is absorbed by the skin. 



B. Secretions. 



On the other hand, the skin is exceedingly well adapted 

 for the purpose of secretion, being the seat of continual growth 

 and decay on the part of the globules ; these processes con- 

 stitute the mechanism of secretion. The furfuraceous de- 

 squamation may be considered as a diffuse secretion; the 

 phenomenon of secretion, however, may be still more clearly 

 observed in the sudoriferous and the sebaceous glands, of 

 whose action the mammary secretion is an exaggerated form 

 of result. 



Fig. 96. Development of the sudoriferous glands.* 



The secretory organs are formed in the ordinary manner 

 from the globular elements of the malpighian layer (Fig. 96). 

 This vegetation sometimes appears in the form of a tube, 



* A, Development of the sudoriferous glands, in consequence of the prolif- 

 tion inwards of cells of Malpighi's layer, e, Epidermis, r, Layer of 

 g, <7, Solid prolongations representing the beginning of the gland 

 . B, Portion of developed sudoriferous canal, t, t, Tunica propria. 



eration 



Malpighi. 



(Ku'lliker) 



e, e, Epithelial layer, 



