256 NUTRITIONAL PHYSIOLOGY 



system may be likened to that of the general in command 

 of a great army. From his headquarters he can see but 

 a small proportion of his troops. Their line of battle 

 stretches for miles beyond his sight. He issues the order 

 for a general advance. His aides ride to the right and left, 

 bearing the word to the commanders of corps and divisions. 

 The simple act of the general has been followed by a train 

 of events which becomes each moment more difficult to 

 trace. The original order is transmitted to officers of 

 lower rank and interpreted by them in conformity with 

 local needs. When the private soldiers are at last put in 

 motion it is at the word of colonels and captains. The 

 impossibility of having the voice of the commander-in- 

 chief the source of guidance in each company is perfectly 

 evident. It is not merely that he is too far removed from 

 most of his men, but that there are too many problems 

 arising at one time. The minor ones must be solved at 

 the discretion of his subordinates. 



So in the living body the will to walk which seems as 

 simple as the dictation of the first order from headquarters 

 is promptly followed by the action of many nervous 

 mechanisms whose function is to distribute impulses and to 

 apply them in helpful sequence. We have no sense of the 

 subdivision which is involved. We cannot analyze the 

 groups of muscular movements which take place. Yet 

 it is plain that there is an apportionment of stimulation, 

 more to this muscle and less to that, without which the 

 effective result could not be secured. How utterly we 

 should fail in the attempt to regulate the part taken by 

 each of a hundred co-operating muscles by giving attention 

 to each in its turn! The efforts necessitated would be like 

 those of the general deprived of his staff and messengers 

 who should seek to ride swiftly from point to point in the 

 endeavor to direct all his soldiers by his spoken word. 

 The organization of the highly developed nervous system 

 is that of a disciplined hierarchy. 



The comparison we have been using can be made to 

 serve even further. We can find in it a place for the af- 



