824 Popular Editions of Station Bulletins of the 



dred plants of each kind were set in the field in the summer of 

 1908 under as uniform conditions as possible and all but one went 

 through the season, one of the cross-bred plants being destroyed 

 accidentally. All the cross-bred plants were standards, as was 

 expected from the laws of heredity. Seed of each of these strains 

 of tomatoes was secured from self-pollinated flowers; and from 

 this seed plants were gro^vn for the winter forcing-house test of 

 1908-9. No first-cross plants were used in this test, but the par- 

 ents were compared with their pure descendants of the second 

 generation. In accordance with the laws of inheritance, planta 

 of the second generation included both standards and dwarfs, but 

 only the standards were used, the dwarfs being '' rogued-out." 

 For the test of the next summer, crossed plants of the first gen- 

 eration were used as well as plants from pure seed of the parents 

 and of the first and second generations; so that the parents and 

 three generations of descendants were compared. In 1910 fourth- 

 generation plants were also grown with the others. In every case 

 dwarf plants were left out of the tests, although some appeared 

 in every generation except the first. 



In all the tests the plants were given as uniform 

 Results. conditions as possible and enough of each kind 



were included to overcome individual variations. 

 They were, of course, subject to drought and other unfavorable 

 influences that affected other tomato fields in the locality, but 

 gave fair yields for the season in each test. It is believed that 

 the influence of the disturbing factors was so evenly distributed 

 that the figures really show the differences due to effects of cross- 

 ing. The data appear in the table on page 4. 



In each of the field tests the crossed plants of the first genera- 

 tion gave both more ripe fruit and a larger total yield than the 

 standard parent. The average gain in ripe fruit was nearly two 

 pounds per plant and in total yield more than three pounds per 

 plant. On the basis of 2,722 plants to the acre (plants set 4 ft. x 

 4 ft.) this would give nearly 2% tons more of ripe fruit to the 

 acre or 4^/2 tons more total yield from the first generation crosses 

 than from the standard parent. This would certainly be a profit- 

 able return for the time and care necessary to secure the crossed 

 seed. 



It is only in the first generation that this favorable influence is 

 likely to be profitable ; for in the second generation, in this case, 

 many plants had to be throAvn away because of return to the 

 dwarf condition; and the average yield of ripe fruit was not in- 



