TILLETIA. 307 



The black spore-powder is developed as an evil-sinelling 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 first oily or greasy, but gradually dries up to 

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



Fig. IdT.— TilUtta liUicc. A, Two spores germinated in 

 moist air ; a short promycelium is developed, and bear.s a 

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

 pairs. Fushion of conidia, germination, and development of 

 a secondary conidium, C, ;irc r\lsn slmwii. B, Two spores 

 germinated in water with ihmijix . i li.i wiiich elongate till the 

 water surf.ace is reached, wlui. tin v t.irm sporidia; the 

 , _, „.., . ... promycelia are septate and tlir iili-ma ] .asses over into the 



Fio. \i}(,. — TilMio, triUn younger cells, (v. Tubeuf del.) 

 StUkiiUj-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. Tubouf del.) 



|)ales. 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 



