ON THE TOMATO 



fertilize one plant with pollen of the other. We 

 know that, as a rule, plants that cannot be cross- 

 pollenized cannot be mutually grafted. The same 

 barriers usually exist in one case as in the other. 



The potato and tomato grafts, however, proved 

 very notable exceptions to this rule. In both 

 combinations, the union between the foreign stems 

 took place quickly, and resulted in a stem as 

 strong as the ordinary stem of either plant. Growth 

 continued, and the plants came to maturity at 

 about the expected season. 



But the results of the strange alliance were 

 interesting to the last degree. 



They must be considered in detail because they 

 have a bearing on one of the most interesting 

 open problems of plant development the question 

 of sap hybridism. 



POTATOES GROWN ON TOMATO VINES 



The tomatoes that grew on the root-stalks of 

 the potato developed much as other tomato vines 

 do, although in some cases it seemed that the 

 vines bore closer resemblance to potato vines than 

 is usual. But the fruit that appeared in due 

 season was a tomato differing in no very obvious 

 respect from other tomatoes of the same variety. 

 They, however, were not of as good quality. 



Meantime the potato roots, which supplied 

 water and mineral salts to the tomato vine above 



[131] 



