6o 



RESEARCHES ON FUNGI 



diverse geotropic phenomena were elucidated by placing very young 

 or half-grown fruit-bodies in the dark, tilting them out of their 

 normal positions, and watching their development. In the absence 

 of light, stipes curved upwards, hymenial tubes grew downwards, 

 and the pileus flesh extended itself horizontally (Plate V., Fig. 41). 



FlG. 21. Polyporux squam^sus. The embryology of fruit-bodies with eccentric 

 pilei. A-E, vertical sections showing successive stages in development. A, 

 a stromatous knob upon which a conical process has arisen. B and C show 

 the origin of the pileus by depression and lateral expansion of the tip of a 

 conical process. At D the stipe has made a geotropic curvature so that the 

 top of the pileus has become almost horizontal. The pileus has now begun 

 its eccentric development. E is a fully-grown fruit-body. Its pileus is very 

 eccentric and has developed hymenial tubes. F-I, young fruit-bodies seen 

 from above. The pilei F and G correspond to those seen at B and C. H, a 

 young fruit-body in which an anterior half of the pileus, a, may be distin- 

 guished from a posterior half, y. The stipe, *. is laterally placed as at D. I, a 

 young fruit-body in which the anterior half of the pileus, x, is growing 

 rapidly, whilst the posterior half, y, has ceased development, s, the stipe. 

 All natural size. 



In most fruit-bodies the stipe is lateral (Fig. 4, p. 28), in a few 

 more or less eccentric (Plate V., Fig. 426), and in rare instances 

 quite centrally situated, like that of a Mushroom (Fig. 22). An 

 attempt will now be made to account for this remarkable variability 

 of form. 



