132 WARFARE IN THE HUMAN BODY 



with some invasions and fail with others. It has only 

 been through an immense period of evolution that the 

 proteins and other food elements have come to stimulate 

 the production of specific enzymes or catalysts, and it is 

 within every clinician's knowledge that in certain condi- 

 tions of health these necessary reactions do not occur. 

 When that is so nutrition fails, and food becomes a poison. 

 If this is correct, and it cannot be doubted, nutrition 

 must be regarded as an actual process of real immuniza- 

 tion, in which secondary and simpler products are used 

 by the organism as food. Although I came to these 

 conclusions before I was aware of their work, it appears 

 that Abderhalden and Weinland hold views of this kind. 

 Weinland states that the subcutaneous injection of cane- 

 sugar produced or elicited invertin. Abderhalden's work 

 on the production of gestational immunity has exceptional 

 value in that it throws some light on the inhibition of 

 the invasive action of the chorionic villi on the uterine 

 wall, and thereby on cancer also, as I have suggested else- 

 where. In the earlier stages of evolution, in all cell life 

 now, and that of the intestinal absorption cells, the in- 

 gestion of foods is due to purely physical causes, i.e. 

 causes which are not sufficiently obscure to be labelled 

 " psychic " when they should be regarded as conditioned 

 reflexes. Like and dislike, choice and rejection, had, 

 and have (as regards cells), no long path to depend on. 

 Such reactions are not even simple reflexes. They depend 

 entirely on surface tension, on the nature of the cell envelope 

 and the body with which it comes in contact. It may 

 be assumed that primitive cells which certainly possessed 

 low and scanty reaction powers took in all things which 

 their physical nature did not reject. Some were innocuous, 

 and some were at once ejected. Some were harmful, 



