SEEDS AND SEED SOWING. 59 



natural processes. The crossing of different seed stocks of 

 the same varieties of plants is generally a great advantage, 

 since it generally results in increased vigor without loss of 

 desirable qualities. Seeds from self-pollenized flowers are 

 not as productive as crossed flowers. Darwin found that cab- 

 bage plants from seed that had been crossed produced nearly 

 three times the weight produced by self-pollenized seeds. In 

 the case of Indian corn, experiments made at the Illinois Ex- 

 periment Station show that while cross-fertilization is not 

 necessary, it is very desirable. Corn grown from crossed 

 seed in nearly all cases was clearly increased in size as the 

 result of crossing. "Plants grown from self-fertilized seed corn 

 were in most cases notably inferior in size and vigor to the 

 plants grown from hand crossed seed or from seed simply 

 selected which was probably naturally crossed. " ' "One plot 

 from self-fertilized seed had nearly half the stalks deformed 

 in such a manner that instead of standing up straight they 

 turned off at a right angle at or neai- the point where the ear 

 was produced, thus showing the tassel on a level with the ear. 

 Many of the tassels were very deficient in pollen." In an- 

 other plot from self-fertilized seed, nearly all the tassels were 

 abortive. All the plots from self-fertilized seed produced a 

 greater proportion of barren stalks or poorly filled ears than 

 plants of the same varieties from crossed seed or from seed 

 naturally fertilized. On the other hand the flowers of barley 

 and wheat are so constructed that their flowers seldom open 

 and, hence, are naturally self-fertilized, but even here arti- 

 ficial crossing results in increased productiveness. 



The effect of cross-pollination is not always apparent in 

 the progeny of the first generation, but is frequently plainly to 

 be seen in the crossed fruit or seed the first year. However, 

 differences may appear as the result of the cross the second or 

 later generation, which were not suspected. When corn is 

 crossed, it is generally believed that the effect of the cross is 

 apparent the first year in the grain, but careful experiments 

 plainly show that flint corn grains which do not show a trace 

 of the admixture of sweet corn the first generation, may pro- 

 duce ears the second generation showing some of the charac- 

 teristics of the sweet corn. The same truth undoubtedly holds 

 as good in the case of other plants. 



