282 USTILAGINEAE. 



attacks the axis of the maize-heads. Its spores are spherical 

 with slightly granular coats, and measure only 4-6/oi in diameter. 

 It causes damage through shrivelling up of the grain. 



Ust. Reiliana Ktihn. This smut frequents Sorghum halepense 

 and S. vulgare (Durra or Indian millet) ; also maize in various 

 parts of Europe and America,^ as well as in Egypt and India. 

 It is called " Hamari " in the Arabic language. 



Kiihn ^ thus describes it : " This species causes the ears of 

 Durra to become large smut-galls of roundish or ovoid shape, 

 with a height of 60-95 m.m. and a diameter of 40-60 m.m. 

 At first the smut is enclosed in a whitish skin, which is ruptured 

 into shreds to allow the escape of the black spore-powder. 

 After the smut-spores are shed, there remains a stiff skeleton 

 consisting of the fibrovascular bundles of the aborted ear." 



The spores are distinguished from those of Ust. maydis by 

 their greater size (9-1 5m), and their almost smooth membrane 

 with very small spines. According to Brefeld, the spores are 

 capable of germination in nutritive solutions after eight years. 

 In the fresh condition they germinate in water to a limited 

 extent, producing multicellular promycelia which give off conidia. 

 In nutritive solutions they germinate and produce thick promy- 

 celia with three or four cells, from which multitudes of conidia 

 {6-12 fx long and 3-5^ broad) are abjointed. The conidia 

 fall off and sprout till the nutritive substratum is exhausted, 

 when they give rise to thread-like conidia which do not coalesce. 

 If kept dry the conidia easily retain their vitality for months. 



Kiihn distinguishes further Sorosporium Ehrenbergii Kiihn on Sorghmn 

 cermiMm. 



Ust. cruenta Kiihn.^ Another parasite on the ears of 

 Sorghum. It is described by Kiihn as follows : " On the 

 spikelets little reddish-brown protuberances of roundish or 

 oblong shape are formed and enclose moderately-sized masses 

 of dark-red smut-powder. If the pustules are very numerous 

 they coalesce with each other, and the branches of the ear 

 become more or less shortened, thickened, and twisted. Where 



1 Norton, "Ustilago Reiliana,'' Botanical Oazette, 1895, p. 462. 

 ^ Kiihn, "Die Brandfonneu der Sorghum-arten," Mittheil d. Ver.f. Erdkmide 

 7M Balk, 1877. 



^ Kiihn {loc. cit.) and Hamburger Garten- Zeiiung, Bd. 28. 

 Brefeld, Heft v., p. 91. 



