PAEASITIC FUNGI AND MOULDS. 17 



the complete development of the fungus is only effected 

 by its transference from one plant to another. This 

 phenomenon may be frequently observed in animal 

 and vegetable parasites, and it seems to be designed 

 in order to secure the preservation of the parasitic 

 species, by permitting it to grow on two plants in 

 succession, of which the development occurs at different 

 periods of the year ; such is the case with the barberry, 

 which is developed in early spring, while wheat is 

 developed in summer. For a long while it was 

 believed that (Ecidium berberidis, Uredo linearis, 

 and Puccinia graminis were so many distinct 

 species; but it is now known, as we have stated, 

 that they are only three successive phases of the 

 development of a single species.* 



Other Uredinece, constituting the modern varieties 



>f Ustilago and Tilletia, are more apt to affect the 



ears of wheat and other grasses. This disease is termed 



>y agriculturists smut or caries (Uredo carbo or 



r Jstilago segetum, and Tilletia caries). The diseased 



rrain merely appears to be of a somewhat darker 



colour, but on pressing it between the fingers, there 



ssues from it a blackish, oily pulp, which smells 



ike rotten fish. Bread made from the flour of such 



corn has an acrid and bitter taste, and although it 



does not appear to be directly injurious to health, 



* So, again, (Ecidium rliamni (Nerpmn or Bourdaine) produce 

 Uredo rubigo-vera and Puccinia coronata of wheat and oats. (Seo 

 Fig. 7.) 







