34^ Vitamines and Deficiency Diseases [June-September 



XL GROWTH IN PLANTS 



Bottomley ( 147, 148) is the only one who claims to have demon- 

 strated the importance of vitamines for the growth of plants. He 

 was able to isolate, from bacterized peat, a substance which proved 

 to be a powerful stimulant of the growth of plants. This substance 

 was obtained from a fraction which corresponds entirely to the 

 Vitamine- fraction. 



XII. INFLUENCE OF DIET ON THE GROWTH OF TUMORS 



The results obtained thus far by applying the Osborne-Mendel 

 diet, or any other similar vitamine-free diet, to animals bearing 

 tumors have not justified the hope we had for this method. One is 

 able partially to arrest the growth of a tumor on such a diet, but the 

 avidity of the tumor for food is so great that its growth proceeds 

 on a diet which is entirely inadequate for the growth of the animal. 

 Some of the recent papers illustrate this point very well. I was able 

 to show (144) that in chickens, on normal diets and inoculated 

 with Rous's spindle-cell sarcoma, there were higher percentages of 

 " takes " and larger tumors than in chickens f ed on unpolished rice 

 even after addition of yeast or sarcoma extract. Different results 

 were obtained with diets of polished rice. Here the tumor did not 

 "take" at all; whereas, in birds fed on polished rice plus yeast, 

 tumors developed in a large percentage of cases. On these restricted 

 diets no metastases were ever noticed. Food containing vitamines 

 undoubtedly had marked influence on the growth of the tumors. 

 Rous (149) has also studied the influence of simple underfeeding 

 and of Osborne-Mendel diets on rats. Flexner-Jobling Carcinoma 

 was not afifected by underfeeding after the tumor had been growing 

 for some time. Spontaneous tumors of mice were affected by re- 

 stricted diets if the feeding of such diets was started before the 

 inoculation. 



Two explanations for these results are available: When the 

 organism is weakened the tumor does not grow as well as it does 

 when the organism is more vigorous; in the case of a vitamine-free 

 diet, the tumor does not receive essential specific nutrients. A great 

 difficulty in such experiments is the fact that it is practically impos- 

 sible to find a vitamine-free diet or a vitamine-poor diet on which 



