642 MINNESOTA BOTANICAL STUDIES. 



fruits have a greater tendency to be irregular than those not 

 crossed. 



It has already been stated that flowers confined under a 

 screen pollinate themselves. In these experiments only one 

 bud was allowed to open under the screen during the time of 

 the experiment, and the cover was left over the plant a week 

 because the flowers were not castrated and were therefore 

 more likely to be crossed. The first tomato produced in this 

 way was one-half the usual size of the variety and contained 

 forty eight seeds, the average number of seeds for the variety 

 being more than two hundred. The results were not always 

 so marked, but on the whole, the fruits produced in this way 

 are below the average size and usually contain fewer than the 

 average number of seeds. The results as to the vines and 

 fruits from such seeds could not be obtained the first year. 



I tried the effects of using large and small amounts of pollen 

 with the following results. My tomatoes produced from large 

 amounts were large and regular, produced a large number of 

 seeds and did not fail to come to maturity in a single instance; 

 while those from small amounts were smaller in size, had 

 fewer seeds, were not so regular in shape and several stopped 

 growing at about the size of a pea. 



I tried pollinating the castrated flowers of the Red Cherry 

 tomato with the pollen of Physalis pubescens, Datura stramo- 

 nium and Solanum nigrum, making about fifty pollinations for 

 each. With the last two, the ovary started to grow in two or 

 three flowers, but they invariably aborted. With the first, I 

 thought I was getting a fruit to develop fully. I got a fruit 

 about two-thirds the usual size of the Red Cherry tomato, which 

 contained only six seeds. I planted two of the seeds the next 

 year and got the Red Cherry tomato, so this must have been an 

 instance of accidental and insufficient pollination in castration. 

 It is very probable that the instances in which the varieties 

 started to grow were also cases of insufficient pollination by ac- 

 cident and that the pollen of the other species mentioned above 

 had no effect whatever. 



Of two flowers pollinated at about the same time, one is some 

 times half grown before the other makes more than enough 

 growth to make certain the fact that fertilization has taken 

 place. The one that makes this rapid growth from the start 

 ripens nearly as much in advance and is larger than the one 

 that stops growing for a time. Other ovaries become aborted 

 at about one-fourth the size of a pea, but hang on the vines for 



