SELECTIVE FERTILIZATION IN POLLEN MIXTURES. 



271 



TABLE IV. 



THE AMOUNT OF HETEROSIS SHOWN BY EACH CROSS-POLLINATION IN THE INCREASE 

 IN AVERAGE WEIGHT OF SEEDS COMPARED TO THE SELF-POLLINATED SEEDS 

 GROWN IN THE SAME INFLORESCENCES. 



in per cent., is +.496 .093. Although the numbers are scanty 

 there is a significant relation between the two. This means that 

 the more unlike the plants are the greater the distinction that is 

 made between the two kinds of pollen. In proportion as the 

 cross-fertilization benefits the immediate progeny in its development 

 the less effective is that pollen in accomplishing the union. 



The same method of experimentation was applied to another 

 plant, the garden tomato, Lycopersicum esculentum Mill. Ad- 

 vantage was taken of plant characters such that the seedlings 

 could be distinguished in both reciprocal applications. Pollen 

 from a variety with entire leaves with a tall habit of growth was 

 mixed with pollen from a dwarf variety with normal, serrate 

 leaves. Tall stature and normal leaves are dominant so that the 

 cross-fertilized and self-fertilized seedlings from one variety were 



1 Number of seeds too few to make averages reliable. 



