THE WHEAT CROP. 65 



it. Being generally dispersed either before the corn is 

 cut, or by the field processes of harvest, the quality of the 

 sample is seldom affected by it to any extent ; the quantity 

 of produce, however, must be decreased exactly in pro- 

 portion to its existence in the crop. This disease is seen 

 also in barley, oats, and various other grasses. 



" Bunt," or " pepper-brand," is due to the attacks of the 

 fungus known as the Uredo (Tilletia) caries or U. foetida. 

 This fungus confines itself chiefly to wheat, in which it 

 attacks the grains only, where its presence is readily 

 recognized by the rounded appearance and dark colour of 

 the grains, and by the unpleasant odour they emit when 

 crushed between the fingers. It may be detected in the 

 young grain even in its earliest stages, and when fully 

 ripe it occupies the whole interior of the seed, without 

 rupturing its skin, merely causing an alteration in its 

 outward form and colour. When examined under a 

 powerful microscope, these fungi appear to consist of an 

 immense number of minute spores of a dark colour, held 

 together by small web-like filaments; these contain, again, 

 infinitely smaller seeds or sporules, and it is supposed that 

 by the absorption of these into the circulation of the 

 growing plant is the disease spread. So minute are these 

 sporules that it has been calculated (Bauer) that a single 

 grain of diseased wheat may contain 4,000,000 of them, 

 each of which could propagate itself. The spores of the U. 

 caries are very much larger than those of the U. segetum, 

 while, at the same time, they possess a very offensive 

 odour, which affects everything with which the} 7 ' come in 

 contact. Unlike the U. segetum,, too, its spores are held 

 together in the ear at harvest time, and are not separated 

 until the process of thrashing, when, owing to their 

 minuteness and numbers, a very few diseased ears are 

 sufficient to infect a large bulk of grain, and thus greatly 



to depreciate its value in the market. Indeed, were it 



5 



