184 BIOLOGY. [BOOK n. 



effect, artificially digested, and mixed then with much sugar, 

 they nevertheless offer no reaction if treated with the reactive 

 of Trommer. 1 



The complex azotised matters assimilated by the tissues are not 

 the only ones which the blood furnishes. Other azotised substances 

 are formed by means of the coagulable principles of the blood, 

 through special secretory organs called glands. These substances 

 are destined to be the specially active agents, the source of] 

 various liquids to which we shall have to refer. Let us cite, as 

 examples, the digestive ferments, pepsine and pancreatine, of 

 which we have just spoken. 



It will be seen from the preceding remarks, how difficult it is 

 to strike the balance of the nutrition of an animal. The 

 alimentary substances are, in fact, only utilized after having 

 undergone a succession of elaborations, of metamorphoses, and, 

 as we shall see, before being eliminated, they are elaborated 

 anew. For the anatomical element is not a passive element 

 allowing itself to imbibe like a filter : it is a living agent, 

 endowed with special needs, which it satisfies, under penalty of 

 death, by choosing amongst the substances in contact with it, 

 by forming sometimes completely the substances indispensable to 

 its nutrition, then by decomposing and rejecting them ; it is an 

 agent at once of synthesis and of chemical reduction. 



It is especially within the nucleus of the anatomical element 

 that its power of chemical attraction and repulsion seems to 

 dwell. In the glycogenical cell, according to 01. Bernard, the 

 sugar only accumulates while the nucleus is persistent ; and in 

 the muscular fibres, the nucleus is persistent as a regulator of 

 the nutrition. 2 



On the contrary, the degeneracy and death of the element 

 would be the consequence of the disappearance of the nucleus. 



1 M. Sohiff, Digestion, t. ii. p. 154. 



2 Cl. Bernard, Progres et Marche de la Physiologic, etc., p. 99. 



