THE CELLULAR CHANGES OF AGE 73 



destroy the living substance itself. 1 The production 

 of these destructive agents is going on at all times, 

 apparently, in all parts of the body which are alive. 

 A striking illustration of this is offered in the stom- 

 ach. The digestive juice which is produced in the 

 stomach is capable of attacking and destroying living 

 substance, and any organic material suitable for food 

 which is placed in the stomach will, as we know, be 

 attacked by the gastric juices, dissolved to a certain 

 extent by them, and so destroyed. Why then does 

 the gastric juice not attack the stomach itself ? This 

 is but one phase of the problem why the body does 

 not continually destroy itself. It has lately been 

 ascertained by some ingenious physiological investiga- 

 tions that the body not only produces the destructive 

 agents, but also antagonists thereto, anti-compounds 

 which tend to prevent the activity of the destroying 

 factors. The whole problem is one of great interest 

 and importance which calls for very much further 

 investigation before we can be said to have arrived 

 at a clear understanding of it. But it helps us much 

 in our conception of cytomorphosis to know that all 

 portions of the body are endowed with this faculty of 

 destroying themselves, for it enables us to understand 

 how it is possible that after the degeneration of a cell 

 it will be dissolved away. It is merely that the 

 agents of solution which are ordinarily held at bay 



1 This remarkable phenomenon is known by the name of autolysis. An ex- 

 cellent general exposition of the subject has been made by Dr. P. A. Levene 

 of the Rockefeller Institute in the Harvey Lectures, 1905-6, p. 73. 



