METHOD IN SCIENCE 13 



be modified in changing internal or external environments. 

 Without the help of chemistry and physiology such a con- 

 ception could hardly have been reached, though a realistic, 

 not verbal, interpretation of Weismannism might have led 

 to the view that " determinants" were catalytic in nature. 

 Since we now recognize such a morphogenetic character of 

 catalysts and hormones, we need assume no other instru- 

 ments until it is shown definitely that they do not and 

 cannot satisfy the equation of life. If biologists had not 

 ignored pathology by following Darwin's lead blindly when 

 he assumed, without a shadow of proof, that unfavourable 

 variations must be without effect on evolution, they might 

 have inquired eagerly into the causes of disease, and have 

 found that much of it must inevitably be attributed to 

 factors, or the want of them, originally taken up from the 

 environment. The simplest example is, perhaps, that of 

 iron, and the latest recognized that of accessory food factors, 

 fat or water soluble. 



If then the success or failure of morphogenesis is to be 

 attributed to such " tools " employed in a particular ener- 

 gizing field of the environment, it is easy to imagine, and 

 even to prove, that they must go over in the sperm or egg- 

 cell, or be re-acquired from the yolk, or from the parent 

 during gestation. Darwin's pangenes can thus be trans- 

 lated into the language of hereditary morphogenetic 

 catalysts. 



Such a statement leads to an inquiry concerning the 

 nucleus of a cell. To what extent do biologists believe that 

 it is alive ? They write of the nucleo-plasm as if it were, 

 but all the physical phenomena of mitosis suggest that it is 

 not o r the complex molecular structure furnished with 

 reversible catalysts dominating and directing anabolic and 

 catabolic processes which we call " life," but that it is com- 



