Fink: lycopersicum esculentum. 643 



a month or two. It is certain that these have been pollinated 

 because flowers castrated and not pollinated always drop off in 

 a week or ten days from the time of castration. I think there 

 are two causes for this difference in development, i.e. insufficient 

 pollination and lack of sufficient nourishment. The first, I 

 think, is proven by the fact that in trying the effect of different 

 amounts of pollen it was those flowers which received small 

 amounts that aborted. As to the second, it is usually the 

 flowers farthest from the base of the cluster that stop growing 

 for a time or abort. The fruits nearer the base begin to grow 

 first and take most of the nourishment till fully grown. 



The process of castration was used so frequently in the ex- 

 periments that a description of it will be in order. The best 

 time to castrate is just when the flowers are beginning to ex- 

 pand. When the flower is fully expanded there is danger of 

 accidental pollination in castration, or that it has been already 

 pollinated. Also the tissues are much softer just as the corolla 

 begins to expand so that the stamens are easier to remove at 

 this time. One way to castrate is to pull off the corolla as the 

 stamens come with it. Another is to pull off the stamens one 

 at a time with small forceps. By the first method the stamens 

 are pulled past the stigma, and in some small tomato flowers 

 there may be remote possibility of accidental pollination even 

 at this time. By the second method the stamens are pulled 

 directly away from the stigma, and the danger of accidental 

 pollination is thus largely avoided. 



The frames on which the screens were spread in these ex- 

 periments were three and one-half feet square on the ground, 

 and four feet high. This was large enough so that the vines 

 did not touch them during the early part of the season when 

 the experiments were performed. I made my first screen of 

 mosquito bar, but threw it aside for others made of cheese- 

 cloth, on account of the smaller meshes. I do not know that 

 the change was necessary, and could not see that the plants 

 were influenced in the least even by the latter kind of screen. 



