238 PHYLU.M VII. CARPOMYCETEAE 



barley, bearing lines or spots of Red rust. First examine a 

 few of the spores mounted in alcohol, with the subsequent 

 addition of a little potassium hydrate. Then make very thin 

 cross-sections thi-ough a rust si)ot, and mount as before, so as 

 to see the parasitic filaments in the leaf, bearing the Red-rust 

 spores upon little stalks. 



(d) In July, August, or September collect stems of wheat, 

 oats, or barley bearing lines or spots of Black rust. Study the 

 teliospores as above, and afterward make cross-sections also. 



(e) In early spring collect and examine the Black rust on 

 wet stems of rotting straw. Look for germinating tehospores 

 and sporids, which sometimes may be found. 



(/) Examine microscopically the gelatinous prolongations on 

 "cedar-apples," and observe the teliospores, which resemble 

 those of Wheat rust. *' Cedar-apples," which are common in 

 the spring on red-cedar twigs, are in reality species of rust of 

 the genus Gymnosporangium. Their cluster cups occur on 

 apple leaves. Uredospores are lacking. 



(g) Collect smutted ears of Indian corn. Mount a little of 

 the black internal mass in alcohol, followed by weak potassium 

 hydrate and observe the spores. 



(h) Make very thin slices of young fresh or preserved speci- 

 mens and examine for parasitic and spore-bearing filaments. 

 The outer tissues of the distorted kernels are generally best. 



(i) Make similar studies of the smuts of wheat, oats, or 

 barley, which may be collected in June, or about the time of the 

 "heading" of the grain. 



(j) Make hanging-drop cultures (in water) of the teliospores 

 of Tilletia and Ustilago, and compare their germination. 



The Imperfect Fungi 



410. There are many fungi (about 16,000 species), in 

 some respects resembling the Ascus Fungi (Ascosporeae), 

 of which we know only the conidial stages. They have 

 been brought together temporarily in three orders under 

 the general name of ''Imperfect F^ungi." 



411. The Spot Fungi (Order Sphaeropsidales) are 

 mostly parasitic on leaves and fruits of higher plants, 



