(^2 MISSOURI AGRICULTURAT, RF.PORT. 



Now there are, if we begin to examine them, a great many causes 

 which prevent this self pollination and they tlo prevent it very efTcctu- 

 ally. One is by having the pollen ripen at a different time from that in 

 which the pistils are ripe, so that when the pollen is ripe the pistils 

 cannot be fertilized and the pollen must be taken to some other flower 

 and when the pistils are ripe they must be pollinated from some other 

 fiower because their pollen is all gone. Another way is by having the 

 stamens some distance from the pistil so that when carried by wind 

 or insects, the chances are small that the pollen will get from the stamens 

 to the pistil of flowers on the same plant. In corn we have the stamens 

 removed a long distance from the pistil because in the corn the stamens 

 are the "tassel," and the pistils are the "silks." You have seen a yellow 

 powder shaking ofif from the tassels when the wind is blowing. It sifts 

 down and the wind carries it along and some of it is sifted on parts of 

 the plants below. This powder is the pollen. Insects do not aid in 

 carrying the pollen of the corn, it depends upon the wind. The silks 

 are connected with what later come to be kernels, so that in the corn we 

 have a mammoth pistil with a very long drawn out filament which is 

 rough or sticky at the end and which gets its pollen sifted down from 

 the tassels. Now if we could take this and examine it under a micro- 

 scope at this time, we should see something interesting going on. The 

 pollen, lighting on the end of the silk, grows out into a tube which 

 carries a cell-nucleus down the silk to where the kernel forms later on 

 and this accomplishes the fertilization. 



The whole structure of the corn plant is one which almost entirely 

 prevents self-pollination. The chances are greater that the silk will be 

 dusted by pollen from another corn stalk than by its own, and I may say 

 here that even if it should be pollinated by pollen from its own stalk, 

 that the pollen from its neighbor would germinate quicker and outrun 

 its own pollen growth. Corn is essentially a cross-pollinating plant. 

 I'his fact has some very distinct advantages. I was not able to find the 

 data on the effects of cross-fertilization in corn, but I found other data 

 which will show what I want to say equally as well. 



Chas. Darwin in his study of cross and self-fertilization has left us 

 valuable records of experiments that he carried on. Here is one with 

 the common Morning Glory. He raised his plants in a green house 

 where he could cover them with a fine net, keeping out all insects, and 

 did the work of pollination with a brush. He pollinated some with the 

 pollen of other plants and some with their own pollen. The first gen- 

 eration the cross-pollinated plants had an average height of 86 inches 

 and the self-pollinated plants of 65 inches, or in the proportion of 100 to 



