HYBRIDIZING PLANTS 139 



It has been known for a long time that hybrids have 

 greater vigor than either of the parents, but Httle use was 

 made of the fact until recently. It is believed that more 

 vigor is given to an organism by dominant characters than 

 by recessive ones. Since the hybrid has a very much higher 

 percentage of its characters conditioned by dominant fac- 

 tors, it is more vigorous, but, for the same reason it does not 

 transmit its vigor to the offspring. Where self-pollination 

 is the rule, more and more characters become fixed. The 

 hybrid field corn grown in 1943 was about 50 million acres 

 in the United States with the twelve corn states planting it 

 in 78 per cent of their acreage, while the larger growers use 

 hybrid sweet or sugar corn almost entirely. "Seed" is pur- 

 chased each year from specialists who grow it. A high per- 

 centage of the chickens grown today are cross-breeds or 

 hybrids. 



The production of hybrids for vigor in garden plants has 

 not been followed by anyone, to the author's knowledge, but 

 it should be a very promising field. Seeds could be used for 

 annual flowers as they are used in corn, but in many other 

 cases the hybrids could be propagated vegetatively. 



Petunia, fox-glove, flowering tobacco, roses, and peas 

 make interesting plants for beginners. Time and patience 

 are essential. It is not a pastime for an odd week-end, but 

 one that must have frequent attention when the flowers are 

 receptive, at which time several hours may be used with 

 little progress. The United States Department of Agricul- 

 ture Yearbook for 1937 describes special techniques for dif- 

 ferent garden flowers. 



If thought, time, and effort are used, and careful records 

 are kept, the reward should measure well above the average 

 for the effort expended. The work of Mendel in the very 

 small garden shows that extensive equipment and space are 

 unnecessary. The changing of a plant or flower by a well- 

 planned experiment is a great thrill. Most of the improve- 



