FUNGI. 



29 



further to the inside. This tendency to pass from the 

 gill- to the alveolar structure is, as a rule, character- 

 istic of the inverted caps. 



Some of De Seynes' cases are ascribed to invagi- 

 nation. 



Ludvvig ascribes the inverted caps of Bussula cle~ 

 pallens to splitting of portions of the upper surface ; 

 the surface of the wound, instead of cicatrising, 

 formed, during moist weather, gills. If this is so, it 

 is certainly a quite novel and unheard of mode of 

 formation for the inverted structures. 



Fig. 4. — Clitocybe clavipes. Upper surface of cap, showing- three inverted 

 stalkless caps caused by invagination from the lower surface. 



Fermond says that the inverted stipeless caps are 

 due to the infolding of the normal hymenial tissue 

 and fusion of the cap-margins behind it ; he found all 

 transitions. 



Grueguen, on the other hand, appears to regard the 

 phenomenon as due to accident, for he ascribes it to 

 lesion of the edge of the cap. 



Origin of the Phenomenon. — The writer may at once 

 state his conviction, surviving in spite of many a pro- 

 test by mycologists and others, that all these cases of 

 inverted hymenium are the expressions of a partial 

 reversion to an ancestral character. 



The most primitive type of fructification is probably 

 that of Glavaria, etc., in which a cylindric or club- 

 shaped branch is uniformly covered with hymenium, 

 which extends down the stalk as well for some distance. 

 Buller figures an abnormality in Lentinus lejrideus, 



