CHAPTER VIA. 



THE DYNAMIC ELEMENT IN LIFE. 



§ 36a. A CRITICAL comparison of the foregoing formula 

 with the facts proves it to be deficient in more ways than 

 one. Let us first look at vital phenomena which are not 

 covered by it. 



Some irritant left by an insect's ovipositor, sets up on a 

 plant the morbid growth named a gall. The processes in the 

 gall do not correspond with any external co-existences or 

 sequences relevant to the plant's life — show no internal rela- 

 tions adjusted to external relations. Yet we cannot deny 

 that the gall is alive. So, too, is it with a cancer in or upon 

 an animal's body. The actions going on in it have no refer- 

 ence, direct or indirect, to actions in the environment. Never- 

 theless we are obliged to say that they are vital; since it 

 grows and after a time dies and decomposes. 



A kindred lesson meets us when from pathological evidence 

 we turn to plwsiological evidence. The functions of some 

 important organs may still be carried on for a time apart 

 from those of the body as a whole. An excised liver, kept 

 at a fit temperature and duly supplied with blood, secretes 

 bile. Still more striking is the independent action of the 

 heart. If belonging to a cold-blooded animal, as a frog, 

 the heart, when detached, continues to beat, even until its 

 integuments have become so dry that they crackle. Now 

 though under such conditions its pulsations, which ordinarily 

 form an essential part of the linked processes by which the 



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