A STUDY OF WHEAT. 29 



the grains, and in the amount of starch and proteine contained 

 in them. In other words, the greatest characteristics are found 

 in those parts of the plant for the sake of which it is culti- 

 vated and in those properties of these parts which, under vari- 

 ous circumstances, are especially useful to mankind. 



The causes producing variation in the vegetable forms are 

 yet under discussion by botanists, although some of them are 

 settled beyond a doubt. One general occasion for the appear- 

 ance of new individuals, differing from the old stock, is the 

 fertilization of the known species, by the pollen-grains of some 

 strange variety. These pollen-grains may come from some wild 

 specimen growing in the adjoining woods, or even from the 

 wheat-fields of some neighboring State. The wheat-fields need 

 not lie adjoining each other in order that the one may fer- 

 tilize the other, for the pollen-grains are so very minute the 

 wind might carry millions of them immediately in front of our 



Pig. 4. Starch Grains of Clawson Wheat, or Clawson Flour. 

 Drawn with the Camera Lucida. X 



eyes, yet we could not see that the air was darkened in the 

 least by their presence. They are so light they can easily be 

 carried miles by the air before they are dropped. Sometimes 

 it happens that a single bud or blossom, for some unaccount- 

 able reason, will develop differently from all the other buds 



