62 MONTHLY CALENDAR. 



squashes, which have two kinds of flowers. By crossing or 

 cross-pollination is meant the pollinization of the female organ 

 by pollen from another plant. The crossing of different varie- 

 ties generally gives increased vigor in the progeny, but its 

 effect is variable and may result in the loss as well as in the 

 increase of their desirable qualities. Most of our cultivated 

 plants are crossed by natural processes. The crossing of differ- 

 ent 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 cabbage plants from seeds that had been crossed 

 produced nearly three times the weight produced by self-pollen- 

 ized seeds. In the case of Indian corn, experiments made at the 

 Illinois Experiment 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 select- 

 ed which was probably naturally crossed." "One plat 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 near 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 another plot from 

 self-fertilized seed, nearly all the tassels were abortive. All the 

 plants from self-fertilized seed produced a greater proportion 

 of barren stalks or poorly filled ears than plants of the same 

 varieties from hand crossed seed or from seed naturally fertil- 

 ized. On the other hand the flowers of barley and wheat are so 

 constructed that their flowers seldom open and hence are natu- 

 rally self-fertilized, but even here artificial 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, differ- 

 ences may appear as the result of the cross the second or later 

 generation which were not suspected. When corn is crossed it 



