PLANT BRieEDING. 1 59 



ingly great the difference was." * It may be well to note also 

 that, associated with the increase in the amount of fruit, there 

 was also an increase in the number of individual fruits, 

 although these, as also the seed, were individually smaller. Van 

 Mons also employed this method of using unripe seeds in his 

 experiments with apples and pears, for the purpose of checking 

 too vigorous growth and increasing the relative fruitfulness of 

 the product. 



Besides increasing the number of fruits, the use of unripe seed 

 also results in early maturity. In the cumulative trials of 

 tomatoes, already mentioned, the strain from immature seed 

 ripened from lo days to 4 weeks earlier, in different years, than 

 did the corresponding series from ripe seed. Such differences 

 in earliness do not always occur, however, and some observers 

 have noted opposite results ; but with the earlier production 

 and the increased percentage of fruit comes also the lowering 

 of vitality and consequent lessened ability to stand unfavorable 

 conditions. In other words, the use of unripe seed is simply a 

 means of checking growth and the usual result follows. Within 

 certain limits checking growth tends to increase fruitfulness, no 

 matter how the check is given. Some have contended that the 

 plants would overcome the initial weakening and upon being 

 subjected to favorable conditions would acquire vigorous 

 growth while retaining the more fruitful habit. Of course this 

 is the end desired as a result of this method of treatment, but, 

 so far as the writer is aware, there is nothing to warrant such 

 a supposition. Experience in breeding tomatoes at this Experi- 

 ment Station indicates that this desired end is not obtained. 



brj;e;ding from asexual parts. 

 The distinction between seedling varieties and bud varieties 

 is one of degree rather than of kind. The different buds on a 

 tree frequently produce offspring possessing quite as distinct 

 individuality as do the different seedlings from the same tree. 

 So the tree should be considered not as an individual but rather 

 as a collection of individuals, the bud being the unit. Now no 

 two buds on a given tree are subjected to precisely the same con- 

 ditions. All of the buds cannot possibly survive, hence arises 



* Arthur, American Naturalist, 29, p. 906. 



