1915] 



OVERHOLTS STUDIES IN THE POLYPORACEAE 



685 



^(P 



or so inconspicuous that close observation is necessary to 

 detect them and I have often examined whole sections without 

 being able to locate them. A similar section taken elsewhere 

 in the hymenium may show an abundance of them. The ac- 

 companying illustrations (figs. 1 and 2) show the different 

 forms they may assume, 

 but perhaps the most 

 common form is as 

 shown in a of fig. 1. 

 They are often scarcely 

 larger in size than the 

 basidia, but are differ- 

 ent in shape, usually „ , „ it , , , 



•+V. +V. 4? £' Section of the hymenium of P. abiet- 



Wltn tne appearance 01 inus showing cystidia and spores. 



slender pegs tapering 



to a rather blunt point. Earely they are somewhat fusiform 



in shape and reach a length of 20 n and a thickness of 6 p. 



These sizes are unusual, however. They are colorless or 



almost so, sometimes scarcely extending beyond the basidia, 

 but sometimes projecting enough that one can easily pick 

 them out with the lo^ 



17 



usually 



of the microscope. They 



small crystals 



rusted, but sometimes 

 somewhat capitate with 



fi 



They 



Fig. 2. Section of the 

 hymenium of P. abietinus 

 showing cystidia incrusted 

 at the apex. 



then much more conspicuous, and in 

 some collections this appears to be the 

 predominating condition. 



Before the writer had seen this 

 more conspicuous type it was thought 

 these sterile, inconspicuous structures 

 might be basidia that had discharged their spores and had thus 

 been rendered hyaline, as it is frequently found in other species 

 that the mature spore-bearing basidia project somewhat be- 

 yond those that have not reached maturity. The shape of 

 these bodies and the fact that they often assume a capitate 

 apex, as do cystidia of many other species, make this view 

 untenable. If more proof were needed it might be pointed 

 out that these bodies are present in young specimens and in 



