228 ORIGIN AND NATURE OF LIFE 



a brilliantly played piece of biological sym- 

 phony by hundreds of thousands of nerve cells 

 and muscle cells playing in perfect harmony, 

 and timed sequence of performance. Nutrition 

 absolutely adapted in quality and quantity 

 must be provided for these skilled players, 

 and this provides work for the great digestive 

 and circulatory systems, which also are 

 regulated and controlled by master nerve- 

 cells both of the central nervous system, 

 and of a special nervous system of their 

 own called the sympathetic nervous system. 

 The food must first be rendered soluble by 

 digestive ferments manufactured by special 

 glands, and poured out into mouth, or 

 stomach, or intestine. The soluble chemical 

 products must be built up upon a system 

 for which each type of animal possesses its 

 own plan and secret device, in intestinal 

 absorbing cell, in liver, and in lymph gland, 

 and each such guild or craft of cells knows 

 its own cunning workmanship, The speci- 

 fically prepared food now chemically built 

 up to the exact chemical pattern, in whatso- 

 ever protean form it may chance to have 

 entered the mouth, so that it can form part 

 of the circulating blood, is borne round in 

 endless circuit by the powerful thrusts of the 

 beating heart. By the branching and re- 



