OABPOPHTTA. 



175 



solve and, the watery portions evaporating, leave a dusty 

 mass of black spores. 



The spores germinate hy sending out a short filament 

 much as in the wheat-rust (Fig. 95, A and 

 B), upon which minute sporids are 

 formed. The subsequent history of the 

 sporids is not known. 



362. Other Smuts, as Grain-smut or 

 Black Blast (Ustilago segetum) of wheat, 

 oats, and barley, and the Bunt or Stinking- 

 smut (Tilletia tritici) of wheat have a 

 structure and mode of development close- 

 ly resembling the foregoing. 



Fio. 96. — Ends of 

 three spore - bearing 

 filaments (spore-sacs?. 



Comparing the spores of the Smuts with those 

 of the precediug orders, we here consider them as 

 sac-spores (ascospores), and the mass of tissues 

 in which they are produced, as a degraded spore- 

 fruit. The orderly arrangement of spore-sacs so of indian-oorn Smut, 

 evident in the Cup-fungi is less marked in the Iporesf' "' a' ^sporl 

 more parasitic Black Fungi : it is scarcely notice- 2*?''J?„„'''.P®- Magni- 



T,i • *i, -D t 1 -1 • *i o . -i^ fled 1800 times, 



able in the Rusts, while in the Smuts it has en- 

 tirely disappeared. As the parasitism increases the structural degra- 

 dation also increases. 



Practical Studies. — (a) Collect smutted ears of Indian corn. Mount 

 a little of the black internal mass in water and obsei've the spores. 



(6) Make very thin slices of young fresh specimens and examine 

 for parasitic and spore-bearing filaments. The outer tissues of the 

 distorted kernels are generally best. 



(c) Make similar studies of the Grain-smut, which may he readily 

 collected in June or a few days after the "heading" of the grain. 



Here should come a great number of reduced Sac-fungi (including 

 the Yeast-plants, p. 110) and the so-called Imperfect Fungi. 



Class IV. Basidiomtcetes {tJie Puff-halls and Toadstools). 



363. The plants of this class are among the largest and 

 fioest of the fungi. They are mostly saprophytes whose 



