PSATHYHELLA DISSEMINATA 47 



of them as being at first grey and finally black. The surface of the 

 gills is even and without the slightest trace of mottfing (Fig. 26, A). 

 This is due to the fact, which will be explained more fully a little 

 later, that the basidia develop their spores in the same manner as 

 Lepiota cepaestipes. In the entire absence of mottling from the 

 gills, Psafhyrella disseminata differs from all the species of Panaeolus 

 and Anellaria. Cystidia are absent from the lateral surfaces of the 

 gills, but are present along the free gill-margins at the periphery 

 of the pileus where they extend centripetally for a short distance 

 only (Fig. 27, E, a, b, c). 



The stipe varies in length from about 2 • 5 to 4 cm. It is thin, 

 for it is not much more than 1 mm. thick, even, tapering upwards 

 very slightly, whitish, weak, easily broken, frequently crooked when 

 the fruit-bodies are congregated, and hollow (Fig. 26, A, p. 44). 

 At its base it may give off radiating fibrils. The surface of the stipe, 

 especially in its lower half, bears a considerable number of hairs 

 which often occur several together in little groups (Fig. 21, A, p. 35). 

 The hairs, which are unicellular, resemble those on the pileus and 

 have inflated bases and cylindrical shafts (Fig. 27, D, b and c). 



The spores are black in the mass on white paper but dark brown 

 when examined with the microscope, smooth, oval, rounded at the 

 end containing the apical pore and more pointed at the other end, 

 9 to 11 /A long, and 4 to 5 /x wide. 



The Spore-discharge Period.— In order to determine the length 

 of the spore-discharge period, I secured a clump of fruit-bodies 

 which were just opening, together with the substratum upon which 

 they were growing, and removed them to a room in a house where 

 they were set in their natural upright position under a bell-jar. 

 Glass slides were then placed under the pilei to collect any falling 

 spores ; and, when one slide was removed for examination with 

 the microscope, another was put in its place. Spores began to settle 

 on the first glass slide at about 11 o'clock in the morning and con- 

 tinued to fall all day. At 1 1 p.m. a new slide was set under the pilei. 

 Next morning at 9.30 a.m., the spore-deposit on the slide was very 

 thin, and all the fruit-bodies had collapsed. These observations, 

 although not so complete as is desirable, show that spore-discharge 

 in Psathyrella disseminata takes place during a period of from 12 to 



