DISEASES OJ 1 WHEAT 157 



field, liming the seed, and soaking the seed over night in com- 

 mon salt lye. Though the efficacy of the remedies was doubt- 

 ed, there must have been some beneficial results, for it is 

 claimed that the seed was invariably steeped. By the middle 

 of the nineteenth century there were many methods of steep- 

 ing, liming and brining wheat to prevent smut. It was found 

 that the use of a solution of arsenic gave a clean crop from 

 smutty seed. 



Just how fully the nature of smut was understood by these 

 early writers does not seem to be clear, but they must have had 

 considerable knowledge of the disease in order to pursue such 

 correct principles in endeavoring to effect a cure. The black 

 dust frequently filling the kernels of ripening wheat consists of 

 thousands of germs of the parasitic smut fungus. These germs, 

 or spores, have a great capacity for spreading over the fields, 

 but the only real danger seems to be from those spores which 

 lodge on healthy kernels, generally in the hairy ends. Chances 

 are slight of clean seed being infected by being sown on 

 ground containing smut spores. Spores have the same func- 

 tion as seeds of higher plants, and, the infected kernels of 

 wheat being sown, the spores germinate at the same time as 

 the wheat. The slender filaments penetrate the tissues of the 

 wheat plant before the first leaf is put forth. From this 

 point its growth is, within the wheat plant, both plants growing 

 together. It seems to be still undecided how these threads pro- 

 ceed below the upper two joints of the mature wheat plant, 

 whether they pass upward through the pithy region of the stalks, 

 or whether they follow the surface tissues, but it is probable 

 that the method of smut growth is uniform throughout the 

 entire plant. The fungus seems to die as it passes upward, and 

 leaves few traces of its path. 



In the mature wheat plant smut seems to be found only in 

 the chlorophyl bearing parenchymatic tissues. Nearly 30 rows 

 of breathing pores in the skin covering of the straw run length- 

 wise with the stalk. Under these rows of pores are layers 

 of succulent cells which produce the food eventually used in 

 forming the wheat grains. The smut filaments remain close 

 to the open pores, absorbing and taking the place of this cellu- 

 lar structure with its chlorophyl and protoplasm. No other 

 cellular tissues are disturbed, and until the heads develop the 



