272 



D. F. JONES. 



visible because of differences in leaf formation and in the other 

 variety by habit of growth. Dwarf plants are characteristically 

 shorter and more compact in stems and leaves which gives them 

 a distinct appearance. The plants used were grown from un- 

 pedigreed seed but the tomato is usually self-fertilized and the 

 varieties employed were tested and found to come true to type. 

 Two experiments were made and the results from these are given 

 as pollen mixtures number 21 and 22 in the appendix. The 

 plants from individual fruits are grown separately. The total 

 numbers in the two mixtures are 340 and 272. Differentiation 

 was sharp in the seedling stage in the A lots with either serrate 

 or entire leaves. In the B lots the presence of tall and dwarf 

 seedlings could be easily seen but not all of them could be 

 separated as positively as could be desired. The plants were 

 therefore set in the field and classified after they had grown 

 about two months. They were set out too late to make a 

 satisfactory growth and even at the end of the season classifica- 

 tion was not made with certainty in every case. 



TABLE V. 



CORRELATION BETWEEN THE AMOUNT OF HETEROSIS, SHOWN BY THE PER CENT. 

 INCREASE IN WEIGHT OF CROSSED SEEDS, AND THE SELECTIVE ACTION IN 

 FAVOR OF THE PLANTS' OWN POLLEN, r = + .496 .093. 



Per Cent. Increase in Weight. 

 5 7 9 ii 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 



c 



O 



I 20 



