THE NEW CELL DOCTRINE 23 



called antitoxin. That the toxins and antitoxins occur has 

 been demonstrated with certainty, but the quantities are so 

 small that we have not yet succeeded in isolating them. 

 From these and other similar phenomena we learn that the 

 condition, composition and structure of the living substance 

 is of fundamental significance, and is, strictly speaking, more 

 important for the comprehension of vital phenomena than the 

 fact that the physical basis of life shows a strong tendency to 

 form cells. 



We may now put into words the deduction which we may 

 draw from to-day's lecture. Our conclusions may be ex- 

 pressed as follows: 



The new cell doctrine still recognizes the importance and 

 significance of cells. Cells remain the units of morphology, 

 but from the physiological standpoint they appear as adap- 

 tations which, especially by their size and proportions, create 

 favorable conditions for metabolism. The living substance 

 is more important to biologists than its tendency to form cells. 

 Hence we consider the chief problem of biology to be the 

 investigation of the structure and chemical composition not 

 of cells, but of the living substance. The new conception has 

 won its way gradually. It corresponds to so fundamental a 

 change of our views that we are justified in describing the 

 new conception as the new cell doctrine. 



