TILLETIA. 



307 



The black spore-powder is developed as an evil-smelling mass 

 in the ovaries of the host, which are completely destroyed except 

 the outer coats. As a rule every grain in an ear is attacked. 

 The smut is at iirst oily or greasy, but gradually dries up to 

 form a hard stony mass enclosed in the fruit-glumes and 



Fig. 167.— Titletia tHtici. A, Two spores germinated in 

 moist air; a short promycelium is developed, and bears a 

 crown of conidia (sporidia), several of which have fused in 

 pairs. Fushion of conidia, germination, and development of 

 a secondary conldiura, C, are also shown. B, Two spores 

 germinated in water with promycelia which elongate till the 

 water surface is reached, where they form sporidia; the 

 ■r, ,,.« ™-,, . . ... ■ promycelia are septate and the plasma passes over into the 



Fio. 166. — Tilletia tntici Jo^mgQT ceUs. (v. Tubeuf deL) 

 StinkinQ-smut of Wheat. Ear of 

 wheat with smut-grains indi- 

 cated black. The isolated spike- 

 let contains two smut-grains, 

 which, as well as the isolated 

 examples, show fissures in the 

 original ovary wall. One smut- 

 grain in section shows the in- 

 terior filled with black spores, 

 but the ovary wall still intact. 

 (v. Tubeuf del.) 



pales. The spores, therefore, do not escape as dust on the 

 field, but remain in the heads and are garnered with the crop. 

 Smutty ears are easily distinguished on the field by their 

 stiff erect position towards harvest-time, as compared with the 

 more or less nodding healthy ears ; their florets also lie more 

 away from the axis of the ear, the chaff-glumes are more spread 



