THE NERVOUS SYSTEM 275 



part which reflexes from the eye, the ear, the skin, the 

 muscles, and the joints play in guiding them. We will to 

 do a certain thing, to walk to a certain point, for example ; 

 perhaps the first step is a volitional act, but subsequent 

 steps, the suiting of these steps to slight unevenness of .the 

 path, the avoidance of many obstacles, the maintenance of 

 the balance of the body as a whole, for we walk not only 

 with the legs but with the entire body, all these things 

 take place apart from any exercise of the will and, for 

 the greater part, in the entire absence of consciousness, 

 although consciousness may, of course, at any time inter- 

 vene. Reflex actions thus play a most important part 

 even in the execution of those movements which we think 

 of as distinctly conscious acts. 



9. Connections of the cerebrum with lower portions of the 

 nervous system; "the way out." Granting that the nerv- 

 ous events at the basis of consciousness occur within the 

 cerebrum, how do these events influence the muscles, the 

 glands, and other organs which do the bidding of the will? 

 What is the way out from this seat of consciousness ? This 

 path has already been referred to in Chapter VII (p. 81). 

 Cells in the gray matter of the cerebrum give off axons 

 which pass downward through the structures of the 'tween, 

 mid, and hind brain into the white matter of the spinal cord. 

 These axons give off along their course collaterals which end 

 in arborizations around nerve cells of the lower portions of 

 the nervous system and, by bringing groups of these cells 

 into coordinated activity, produce definite volitional move- 

 ments. The student should review carefully in this connec- 

 tion what has already been said with reference to these 

 neurones (see Fig. 165, v). 



10. Connections of the cerebrum with lower portions of the 

 nervous system; "the way in." The fact that afferent 

 impulses from our sense organs of sight, hearing, etc. may 

 affect consciousness indicates that there must be some 



