3 I2 



BIOLOGICAL PHYSICS 



finally to their peripheral terminal extensions, in the 

 various textures, and organs, of the body, and there we 

 have discovered, to our own satisfaction, in the multi- 

 tudinous nerve terminal arrangements, the required 

 mechanism, and means, of securing the excretion, or 



S1V 



S.I 



FIG. 128. SECTION OF EPIDERMIS FROM THE HUMAN HAND. Highly 

 magnified. (Ranvier. ) 



H, horny layer, consisting of s, superficial horny scales ; sw, swollen-out horny cells ; 

 s.l, stratum lucidum ; M, rete mucosum or Malpighian layer, consisting of 

 />, prickle-cells, several rows deep ; and c, elongated cells forming a single stratum 

 near the corium. The granular cells of Langerhans, which lie just below the 

 stratum lucidum, are not shown, , part of a plexus of nerve-fibres in the 

 superficial layer of the cutis vera. From this plexus, fine varicose nerve-fibrils 

 may be traced passing up between the cells of the Malpighian layer. 



elimination, of the used-up neuronal, or nerve cell, secre- 

 tion. This process is effected, in varying, but kindred 

 manner, alike on the surface of the skin, of the mucous, 

 and serous, linings, of the various tubes, or vessels, glands, 

 cavities, and viscera, and amid the muscular elements of 

 the body, wherever the systemic nervous system penetrates, 

 in short, wherever a nerve fibril terminates, whether 

 systemic, or sympathetic, sensory, or motor. 



