THE FUNGI WHICH CAUSE PLANT DISEASE 317 



numerous, hyaline, with very thick, often lamellate walls; fertile 

 cells very light colored, orange-yellow appearing as if immature, 

 chiefly subspherical or spherical, with prominent conical tubercles 

 which extend out 2-3 n to the hyaline envelope, chiefly 19-25 y. 

 in diameter (including envelope.) 



On Hordeum nodosum in Texas. 



T. hordei Kcke is an Asiatic form on Hordeum. 



T. secalis (Cda.) Kiihn. occurs on rye in Europe.^^ 



T. horrida Tak.^^- i^i- "s 



Sori in the ovaries more or less destroying them, completely 



Fig. 232. — Tilletia tritici. A. Two spores germinated in 

 moist air, promycelium and conidia, several of which have 

 fused in pairs. Secondary conidia at C. B. Spores ger- 

 minated in water, promycelia elongate, septate. The pro- 

 toplasm jjasses over into the younger cells. After Tubeuf. 



concealed by enveloping glumes; spores usually present in different 

 stages of development, the mature spores almost opaque, chiefly 

 subspherical to spherical, with very coarse hyaline or slightly 

 tinted, somewhat curved, scales which show at the circumference 

 of the spore as a band about 2-4 n wide and on its top as polyg- 

 onal areas 2-3 n across; hyaline membrane more or less evident 

 and often at one side in a short thread-like projection, 22-33 /* 

 in length. 



Cross sections of stems bearing smutted heads reveal the my- 

 celium in the chlorophyll parenchyma between the fibrous tissue.''* 



On rice in America and Asia. 



