276 PLANT-BREEDING 



They include the cereals, the peas, some leguminous forage 

 crops, and a small number of other agricultural plants. As 

 an instance, I choose the system of the wheat. It embraces 

 seven divisions, which are indicated by the name of types. 

 They are distinguished by the qualities of the ear which may 

 be long or short, tight or brittle, and densely or loosely cov- 

 ered by the spikelets. In the first place comes the widely 

 known type of the Squarehead with its butt-ended ears. 

 From this are derived varieties with ovate ears, whose broad- 

 est part is seen in the middle. CyHndrical ears arc of the 

 same breadth throughout their whole length, but in one type 

 they are almost square and in another more or less flattened. 



These types are further subdivided, according to other 

 marks, each of them embracing some four or five groups 

 of minor value. They are distinguished by the color, size 

 and form of the grains, the marks of the scales, the occur- 

 rence or absence of awns and other similar marks. All 

 these seemingly insignificant characters have been shown to 

 be constant in the pedigree cultures, and an exact study 

 of them enables the breeder to recognize each single type. 

 So it is also with the minor marks, by which the single kinds 

 are finally distinguished. Often these are almost invisible 

 to the inexperienced eye, and years of persevering study are 

 necessary to obtain the faculty of recognizing them easily 

 and rapidly. 



With this object in view a division of labor has been 

 established, finely adjusted instruments for measurements 

 and comparison have been invented, and large collections 

 of samples and pictures have been brought together. Each 

 of these points now demands our special attention. 



Division of labor has been the first requirement, the study 

 being so extensive that it was impossible to take more than 

 one agricultural species into consideration at a time. 

 The panicle of the oats, which was described in our last 



