98 SMUT OF WHEAT, OATS AND BARLEY. 



external dry or other conditions, produce, on germination, 

 extremely fine attenuated threads, as illustrated at O and F. 

 These attenuated threads are also produced on and in the ground, 

 and they secure access to cereals in the following manner : — 



After the seeds of wheat, oats, and barley have been planted, 

 the first green leaf from the seed speedily appears above the 

 ground. In order to perform its vital functions, every leaf is fur- 

 nished on its under surface with an immense number of minute 

 orifices, which lead direct to the inner substance of the leaf. 

 Through these litde openings (termed stomata), the plant 

 parts with moisture in the form of fine vapour. In damp weather 

 every little opening or mouth stands naturally wide open. At the 

 same time, the yeast-like buds belonging to the Smut-fungus are 

 protruding their fine threads, as at O and F, upon the ground. 

 These threads come in contact with the first young leaves of 

 cereals, and enter amongst the tissues of the infant plants of 

 wheat, oats, and barley by the minute open mouths or organs of 

 transpiration belonging to the back of the leaves. When the 

 fine Smut-threads are once within the substance of the young 

 cereals, they are in their natural position. They speedily find 

 their way to the young stems, and, as the stems grow, the fungus 

 grows too, and is carried up by the growing stems. When 

 the ear or panicle is formed, all its parts, including the finest 

 stalks, are invaded by the fungus, and in these parts of the 

 plant it matures itself and produces its innumerable black seeds or 

 spores which burst through the plant from its apex, and from this 

 position once more reach the air and the ground. 



It may be noted that the fungus can grow on no other plants 

 except cereals and grasses. 



The Smut-fungus grows on a considerable number of wild 

 grasses, in waste places, such as darnel and the various wild oat, 

 barley, and rye grasses. 



