204 



In cross sections of the hymenium these hyphae are, of course, 

 cut transversely and appear as circular thick-walled rings made 

 more conspicuous by the light they refract (Fig. 3). It is also 

 seen that they vary much in diameter, from the maximum size 

 down to such sizes that make them almost indistinguishable from 

 the ordinary hyphae. There is no regularity in the distribution 

 of these hyphae as revealed in cross sections. 



The writer was the first* to call attention to the fact that these 

 peculiar hyphae are also present in great abundance in the con- 

 text of the pileus. This fact makes the determination of the 

 species an easy matter. Here the true nature of these hyphae 

 becomes at once apparent if a bit of the context is teased out in 

 KOH. They can be best described as having the general shape 

 of setae but much larger in size. As stated previously and as 

 will be seen from the illustration (Fig. 5) these bodies have a 

 sharp-pointed apex and are largest just back of it. Farther back 

 they gradually become smaller and smaller until they reach the 

 diameter of the ordinary hyphae of the context and are indis- 

 tinguishable from th(?m. Consequently it must be admitted 

 that these seta-like bodies are the modified ends of ordinary 

 hyphae. Their origin also explains why they can not be traced 

 for any considerable distance in sections as stated above. 



It is difficult to even surmise what the function of these extra- 

 ordinary bodies may be. No doubt their presence gives support 

 to the sporophore and to the walls of tubes in which they occur, 

 but it is doubtful if this can be considered more than an accidental 

 function. The fact that the sporophores are not of the type to 

 require such support, being much firmer than in many species, 

 coupled with the knowledge that their duplicates are not known 

 to exist in more than one or two other species of fungi and that 

 fungi show very little hyphal differentiation of any sort, all point 

 to the conclusion that at present they must be regarded as struc- 

 tures whose function is entirely unknown. It may be pointed 

 out, however, that their presence in large numbers might be the 

 means of deterring insects or other destructive animals of a smaller 

 type from feeding upon the plants. Such a function has been 



* Polyporaceae of the Middle Western United States, p. 51, 1915. 



