64 RESEARCHES ON FUNGI 



similar disposition of hy menial surfaces has been observed in nature 

 by others for Hydmum repandum. Two fruit-bodies of Polyporus 

 varius which were recently brought to me, had a quite normal 

 appearance except for the fact that very shallow hy menial tubes had 

 developed on the tops of the pilei. The cause of the formation of 

 these monstrosities still remains to be elucidated. The abnormal 

 pileus of P. squamosus first of all developed hy menial tubes on 

 its under surface. As it continued to enlarge it gradually fell by 



FlG. 23. — Polyporus squamosus. Section through part of a pileus 

 with hymenial tubes on the upper as well as on the lower 

 surface. About § natural size. 



its own weight, until on one side its plane looked downwards at an 

 angle of about 45°. At this stage a new layer of tubes grew upwards 

 in an irregular manner on the pileus top. It seems likely that the 

 unusual displacement of the fruit-body in some way initiated this 

 development. 



Owing to their wonderful power of undergoing unilateral de- 

 velopment, the fruit-bodies of Poli/porus squamosus are admirably 

 adapted for securing a successful liberation of their spores. The 

 hymenial tubes come to look downwards upon an open space as far 

 from the tree trunk as possible, and the stipe is so placed that it 



