THE FOUR LAWS OF AGE ~ 49 



character. You ought to know that the interpreta- 

 tions which I have offered you are still largely in the 

 personal stage. Whether my colleagues will think that 

 the body of conceptions which I have presented are 

 fully justified or not, I cannot venture to say. I have 

 to thank you much, because between the lecturer and 

 his audience there is established a personal relation, 

 and I feel very much the compliment of your presence 

 throughout this series of lectures, and of the very 

 courteous attention which you have given me. 



To recapitulate for we have now arrived at the end 

 of our hour it must be said first that all of the conclus- 

 ions presented are based upon the laws of cytomor- 

 phosis, in other words, of the change in structure which 

 occurs not only in a single cell, but progressively in 

 successive generations of cells. We can formulate the 

 following laws of cytomorphosis: 



First, cytomorphosis begins with an undifferenti- 

 ated cell. 



Second, cytomorphosis is always in one direction, 

 through progressive differentiation and degeneration 

 towards the death of the cells. 



Third, cytomorphosis varies in degree characteris- 

 tically for each tissue (hence in the adult higher ani- 

 mals nearly all stages of cytomorphosis may co-exist). 



We may add that reversed cytomorphosis is not 

 known to occur, or, in other words, differentiated ma- 

 terial cannot be restored to the undifferentiated con- 

 dition. 



Finally, if my arguments before be correct, we may 



