124 CREATIVE EVOLUTION ichap. 



action of these nerves is subordinated to the action of 

 those which stimulate the locomotor muscles — in this 

 sense, that the muscles begin by expending without cal- 

 culation, thus consuming glycogen, impoverishing the 

 blood of its glucose, and finally causing the liver, which 

 has had to pour into the impoverished blood some of 

 its reserve of glycogen, to manufacture a fresh supply. 

 From the sensori-motor system, then, everything starts; 

 on that system everything converges; and we may say, 

 without metaphor, that the rest of the organism is at its 

 service. 



Consider again what happens in a prolonged fast. It 

 is a remarkable fact that in animals that have died of 

 hunger the brain is found to be almost unimpaired, while 

 the other organs have lost more or less of their weight 

 and their cells have undergone profound changes. 1 It 

 seems as though the rest of the body had sustained the 

 nervous system to the last extremity, treating itself 

 simply as the means of which the nervous system is the 

 end. 



To sum up: if we agree, in short, to understand by 

 "the sensori-motor system" the cerebro-spinal nervous 

 system together with the sensorial apparatus in which it 

 is prolonged and the locomotor muscles it controls, we 

 may say that a higher organism is essentially a sensori- 

 motor system installed on systems of digestion, respiration, 

 circulation, secretion, etc., whose function it is to repair, 

 cleanse and protect it, to create an unvarying internal 

 environment for it, and above all to pass it potential 



1 De Manaceme, "Quelques observations experimentales sur l'in- 

 fiuence de l'insomnie absolue" (Arch. ital. de biologie, t. xxi., 1894, pp. 

 322 ff.). Recently, analogous observations have been made on a man 

 who died of inanition after a fast of thirty-five days. See, on this 

 subject, in the AnnSe biologique of 1898, p. 338, the resume' of an article 

 (in Russian) by Tarakevitch and Stchasny. 



