1916) Fomes OFFICINALIS (Vill.) 195 
and possibly others by protective secretions. The sporophores of 
F. officinalis are soft, with a very thin crust that frequently does not 
long persist, but this abundant secretion of resins provides against 
destruction by weather and by animals. An examination of many old 
and dead fruits has shown that in no single instance have insects or 
other animals assisted in their disintegration—this seems to be effected 
slowly and solely by the weather, and the youngest strata are the first 
to go. I have seen lichens on a very old dead fruit. 
Support of this view is afforded by Tschirch™* who concludes after 
his extensive classical researches on resins, that they are not waste pro- 
ducts but of definite biological purpose; elaborated and not katabolic 
materials. In the same connection (24, p. 9) Tschirch also affirms the 
economic value of ethereal oils to their plant possessors, noting that 
among other uses they serve as solvent and thinning agents of resins. 
This calls to mind the fact that the odour characteristic of F. officinalis 
indicates the presence of an ethereal oil and suggests a reason for its 
production, especially in connection with the secretion of the resins. 
Regarding the position of the resinous secretions on the hyphae of 
F. officinalis there is no doubt—they lie on the exterior surfaces of the 
threads; but concerning the way in which they are secreted and the 
source of the materials there is a sharp difference of opinion. Harz! 
appears to be the first to have considered these questions and he informs 
us that the resins are formed as little droplets just within the external 
surface of the hyphal walls, covered as it were by a cuticular membrane. 
He believes that they are formed from the wall substance, and in sup- 
port of this view states that the walls continually become thinner and 
frequently completely disintegrate. Tschirch? confirms both Harz’s 
observations and conclusions, except that he finds no evidence of the 
extreme reduction of the walls, maintaining that though reduced to 
great tenuity they are always intact. He holds that the greater part 
of the wall consists of a ‘‘schleim”’ layer which contains resinogen, that 
this layer is the ‘laboratory of resin production”’, and that this is the 
only case in which a cell wall is known with certainty to be the sole 
source of the resin secretions. Zellner?’ is doubtful about the wall 
being the source of resin, or as he phrases it “disorganization products 
of the fungus membrane”’; this thesis he affirms is not proven. 
I am convinced from my own observations that there is a frequent 
thinning of the hyphal membranes in the sporophore, and also that 
disintegration to a limited extent occurs. But I have observed that 
this thinning phenomenon likewise occurs in certain non-resinous 
polyporous sporophores and so by itself is of no weight in supporting 
Tschirch’s dogma. On the other hand there is no support offered for 
