1915] 



OVERHOLTS — STUDIES IN THE POLYPORACEAE 681 



preparation made in this manner will often show spores when 

 other methods of demonstrating them have failed. 



Even with the most careful manipulation one will some- 

 times fail to find the spores, and, indeed, some species seem 

 to be almost always sterile. In the case of Fomes fomentarius 

 I cut sections of all the specimens available, and only when 

 as a last resort, I sectioned a small and very unpromising 

 specimen did I find the spores. I have been able to locate 

 them in but one of the few specimens of Polyporus graveolens 

 that were available for examination. 



As stated above, the literature dealing with American Poly- 

 poraceae contains many inaccurate observations concerning 

 spores. This is due mostly to a lack of care in making sure 

 that a given body in the hymenium is really the spore of the 

 fungus in question. The writer is of the opinion that spores 



should not be recorded for a collection unless they are ob- 

 tained from a spore print or are seen attached to basidia. 

 The spores found on basidia are usually somewhat immature, 

 at least as regards size, but from their shape one can judge 

 whether the spores found free-floating in the mount have any 

 relation to the species under consideration. Where such free 



spores alone are present there is always the possibility that 

 they belong to some other fungus and they should not be 

 taken into consideration unless present in large numbers. 

 One must also guard against the fact that the cut ends of 

 hyphae may be in such a position as to appear globose in form 

 and such may be mistaken for spores. 



Examining the context hyphae. — In obtaining the char- 

 acters of the hyphae of the context a bit of tissue is picked out 

 with the forceps and mounted on a slide in a drop of KOH 

 solution. In the case of some of the species of the genus 

 Fomes where the context is hard and woody, it is usually 

 better to boil a bit of the context in a KOH solution for a 

 few minutes. In this way the tissue is softened and when 

 teased apart on the slide with needles, a cover glass added, 

 and pressure applied, the hyphae will generally separate out 

 so that their characters may be obtained. In all cases the 



