44 



RESEARCHES ON FUNGI 



which, owing to their large size and striking form, attract general 

 attention as they come up in open woods (Fig. 14). The pilei 

 consist of broad plates which are often as much as 20 cm. in 

 diameter and raised 25 cm. above the ground. The place of 

 attachment of the stipe to the pileus flesh is very high, so that 

 it is evident that it must be situated 1-2 cm. above the centre 



of gravity of the whole pileus in 

 large fruit-bodies (Fig. 15). The 

 stipe can easily be pulled out 

 from the pileus, and after its 

 removal one may observe that it 

 has a flattened top. The free 

 pileus can again be set on the 

 upright stipe. If, when this has 

 been done, one tilts the pileus 

 by pressing down one side of 

 it with the finger and then lets 

 it go, it swings back into its 

 original horizontal position. This 

 could not happen if the centre 

 of gravity of the pileus were in 

 any other situation than that of 

 stable equilibrium. Whilst a 

 fruit-body is growing in nature, 

 so far as I have observed, the 

 pileus is fairly firmly fixed 

 upon the stipe, and does not 

 swing appreciably about its place 

 of attachment during winds. 

 However, to what extent the peculiar position of its centre of 

 gravity enables it to take up and maintain its most stable position 

 during expansion, still remains to be investigated. 



The oldest function of the centric stipe, from the phylogenetic 

 standpoint, is undoubtedly that of providing a free space between the 

 pileus and the ground, so that the falling spores may be carried off 

 by lateral movements of the air. A space of this kind is already 

 present in such primitive fruit-bodies as those of Craterellus cornu- 



FlG. 14. Lepiota procera the Parasol Fun- 

 gus. Fruit-body growing among grass. 

 Photographed at Sutton Park, War- 

 wickshire, by J. E. Titley. | natural 

 size. 



