THE FAMILY OF GRASSES 345 



In the case of the small grains, the penalty of 

 specialized breeding in which selection has been 

 made generation after generation with reference 

 to the quality of the seed has been the gradual 

 loss on the part of many varieties of the cereals 

 of the power to ward off the attacks of a fungus 

 pest that finds their stalks its favorite feeding 

 ground. 



This pest is known to the farmer as "rust," 

 because in many forms it gives to the stalks of 

 the plant, once it is fairly lodged and under de- 

 velopment, a blotched, reddish brown appearance 

 suggestive of the scales of rust that appear on a 

 metallic surface. 



To the botanist the fungus is known as a mem- 

 ber of the tribe of so-called Vredinece or Cup 

 Fungi. The most familiar species is known as 

 Pucdnia graminis. 



The precise history of this parasite has been 

 very difficult to trace. It is known, however, 

 that the germinal matter lodges on the stalks 

 of the grain in the form of minute spores, and 

 that these send little rootlets into the substance 

 of the plant cell and sap its vitality. 



It is further known that at one stage of their 

 career some varieties of rust plant lodge on the 

 leaves of the common barberry and there develop 

 another type of spores. This fact has made the 



