THE NERVOUS SYSTEM. 209 



during rain, to bring their hands together over their heads, 

 or over a branch overhanging their heads. The reverse 

 direction of the hairs, when the arms were in this position 

 caused the rain to run off. Thus, even yet, the direction 

 of the hairs on our lower arm testifies to this advantageous 

 habit of our Ape-ancestors. 



If the skin and its appendages are minutely examined, 

 Comparative Anatomy and Ontogeny supply many similar 

 important "records of creation," showing that they are 

 directly inherited from the skin-covering of the Ape. We 

 obtained our skin and hair by inheritance, immediately 

 from Anthropoid Apes, these from the lower Apes, which, 

 in turn, inherited the same parts from lower Mammals. 

 This is also true of the other great organ-system which 

 is developed from the skin-sensory layer — of the nervous 

 system and the sensory organs. This very highly developed 

 organ system, which performs the highest vital functions — 

 those of the mind — we have inherited immediately from 

 the Apes, and mediately from Mammals of a lower order. 



The human nervous system, like that of all other 

 Mammals, is, in its developed condition, a very complex 

 apparatus, the anatomical arrangement and the physiological 

 activity of which may, in general terms, be compared to a 

 telegraph system. The central marrow (medulla), or cen- 

 tral nervous system, represents the principal station, the in- 

 numerable "ganglion cells" (Fig. 7, vol. i. p. 129) of which are 

 connected with each other and with numerous very delicate 

 conducting lines by their branched processes. The latter 

 are the peripheric " nerve fibres," distributed over the whole 

 surface of the body; these, together with their terminal 

 apparatus, the sense-organs, etc., constitute the "conductive 



