372 THE PROLIFERATION OF CANCER 



Deductions from experimentation in vitro, no 

 matter how well they may harmonise with know^n 

 facts, are not sufficient to act as a basis on which to 

 proceed to find the prevention and cure for the disease. 

 It is necessary at least to try to prove one's work 

 definitely. To accomplish this would not be, we knew, 

 an easy matter. It would be necessary to produce 

 a cancerous growth in healthy animals with the sub- 

 stances which were believed to be the cause of the 

 disease. The chemical auxetics, in correct combination 

 with an alkaloid of putrefaction such as choline, would 

 have to be inoculated into or applied to an animal, and 

 before one could say that the combination is a cause of 

 cancer a malignant growth would have to appear at the 

 site of inoculation. The experiment would have to be 

 frequently repeated, and careful precautions would have 

 to be taken against possible fallacy. 



It was realised that it would be quite useless merely 

 to inoculate a solution of, say, kreatin and choline sub- 

 cutaneously into an experimental animal, because it is 

 obvious that such a solution would rapidly be excreted, 

 and we know from in-vitro experimentation that before 

 a cell can divide, either by a normal or an asymmetrical 

 division, it must be subjected to the chemical agent for 

 a certain length of time. It would be necessary to 

 create a sore, because a chronic healing site is essential; 

 and this would not be readily accomplished in experi- 

 mental animals, which are not easy to keep quiet, and 

 in which the local application of substances to sores 

 offers practical difficulties. 



