BOLBITIUS FLAVIDUS 



65 



opens out, they become dull chocolate-yellow. Eventually some of 

 them often become powdered on one side with the spores. 



The stipe is usually from 6 to 9 cm. high when fully elongated, 

 but occasionally it attains a height of 12 to 13 cm. Its base is some- 

 what swollen and 0-5 to 0-6 cm. in diameter. The main shaft is 

 cylindrical or very slightly tapering upwards. At its centre it is 

 usually 0-3 to 0-4 cm. thick but, in very large fruit-bodies, it may 

 be 0-5 to 0-6 cm. thick. Its general colour is white tinged with 

 yellow. Below, its surface is somewhat roughened with whitish 

 fibrils, but above, just beneath the pileus, it is smoother and exhibits 

 longitudinal striae. Within, it is hollow. As a whole, it is very 

 fragile like the stipes of many Coprini. 



Fig. 31. — Cystidia of Bolhitius flavidus. A, cheilocystidia at the free edge of a 

 gill. B, two cheilocystidia with a drop of excreted fluid at each apex. C, three 

 cheilocystidia- showing protoplasm and vacuoles. D, a pleurocystidium from 

 the side of a gill, showing shape and contents. E, caulocystidia from near 

 the top of the stipe. Magnification, 293. 



There are no pilocystidia on the top of the pileus, but the other 

 three types of cystidia are all represented. (1) The cheilocystidia, 

 disposed along the free edge of each gill (Fig. 31, A), are ventricose 

 below and extended above into a short cylindrical neck. They 

 contain a large vacuole (C), and sometimes one finds a drop of fluid 

 excreted at their apex (B). Size : 30-50 /i long, 12-20 /* wide. 

 (2) Pleurocystidia, scattered on the sides of the gills, are but rarely 

 seen (D) and in some specimens possibly may be entirely absent. 

 They are ovate-cylindrical, contracted into a short stalk at the base, 

 and bluntly rounded at the apex ; and each contains a large vacuole. 

 Size : about 60 /a long and 20 /a wide. (3) The caulocystidia, toward 

 the top of the stipe, occur in tufts and consist of simple or branched 

 hyphae of somewhat variable shape (E). Size : 50-80 /a long, 

 10-30 IX wide. 



The spores are oval, 11-12 /i long and 7 /* broad, bright yellow 



VOL. III. F 



