THE SKIN. 



show degenerative processes, which are possibly due to the forma- 

 tion of the keratohyalin (Mertsching, Tettenhamer). These karyo- 

 lytic figures and keratohyalin possess in common many apparently 

 identical microchemic peculiarities, and it is very probable that 

 karyolysis and the formation of keratohyalin are processes origin- 

 ally very closely allied i. e. t that the keratohyalin is derived from 

 the fragments of the dying nucleus. 



The stratum corneum forms the outer layer of the epidermis and 

 presents, as a rule, a somewhat differentiated lower stratum. This 



Stratum corneum. 



Stratum Malpighii. 



Duct of sweat- 

 gland. 



Corium. 



Subcutis. , 



~~ 'Blood-vessel. 

 Sweat-gland. ' 



Fig. 304. Cross-section of skin of child, with blood-vessels injected ; X 3- 



latter is more especially noticeable in those regions in which the 

 stratum corneum is highly developed, and is known as the stratum 

 lucidum. It is quite transparent, this property being due to the 

 presence in its cells of a homogeneous substance, which is in 

 all probability a derivative of the more solid keratohyalin of 

 the stratum granulosum. The cells of the stratum corneum are 

 more or less flattened and cornified, especially at their periphery. 

 This applies more particularly to the superficial cells. In the inte- 

 rior of each cell a more or less degenerated nucleus may be seen, 

 but otherwise its contents are homogeneous, or, at most, arranged 



