10 RESEARCHES ON FUNGI 



ended about 10.45 the next morning, and was therefore only about 

 15 hours long. 



The two fruit-bodies left undisturbed in the greenhouse were 

 tested for spore-fall in the morning. Between 10 and 10.30 a.m., 

 a thin but distinct deposit of spores accumulated on slides placed 

 beneath the pilei. Between 10.30 and 11 a.m., a very faint spore- 

 deposit was formed. Between 11 a.m. and 12 noon, a few scattered 

 spores fell. Assuming that the beginning of the spore-discharge 

 period for the undisturbed fruit-bodies took place at the same 

 moment as for the fruit-body removed to the house, we may con- 

 clude that the length of the spore-discharge period for the undis- 

 turbed fruit-bodies was slightly over 15 hours. 



By 3 p.m., i.e. about 4 hours after the cessation of the dis- 

 charge of spores, the fruit-bodies in the greenhouse were observed 

 to be withering : their pilei were sinking downwards. At 7 p.m., 

 one fruit-body had already collapsed, its stipe having broken across 

 in the middle, and the other seemed to be tottering as if about to 

 fall. Next morning both were completely collapsed and appeared 

 to be dead. 



These observations demonstrate how brief is the duration of 

 the period of spore-discharge in the fruit-bodies of Lepiota cepae- 

 stipes, and for how short a time the expanded pilei are spread out 

 before collapsing. We shall see that with this ephemeral existence 

 of the fruit-bodies the general structure and the mode of functioning 

 of the gills is strictly correlated. 



The Gills. — While the pileus is still barrel-shaped and as yet 

 unexpanded, the gills are closely packed together. The packing 

 is shown in the transverse section through a young pileus illus- 

 trated in Fig. 4. As the pileus opens, the gills become drawn apart 

 and, when the spores are being shed, the interlamellar spaces 

 provide ample room for the successful escape of the spores (Fig. 5). 

 Each gill is wedge-shaped in cross-section (Figs. 4 and 5) and 

 positively geotropic so that, as shown in Fig. 5, every part of the 

 hymenium in a normally oriented fruit-body comes to look more 

 or less downwards. The spores are discharged with violence from 

 the basidia, as in other Hymenomycetes. Their trajectories have 

 been represented diagrammatically in Fig. 5. The horizontal part 



