38 Journal of Agricultural Research voi. xii, no. 2 



Hyphenated compound words, like "appressed-downy," "felty- 

 woolly," indicate a condition intermediate between the two names, while 

 "downy to appressed" means that the older portions are downy, while 

 the yomiger portions are appressed. 



In all of the tubes the growth of the fungus is both lateral and longi- 

 tudinal. Of course, the lateral extension is very limited, since the inside 

 diameter of the tubes is only about 20 mm., while the length varies with 

 the length of the agar in the tube. The first record for growth shown in 

 all the tables is always that of the lateral growth. For instance, a record 

 showing 20 by 30 mm. means that the lateral growth was 20 mm. and the 

 longitudinal 30 mm. When the same set of figures are repeated for two 

 intervals of time, like 60 days, 20 by 80 mm., and 80 days, 20 by 80 mm., 

 this indicates that the growth of the fungus had reached the bottom of 

 the tube at the first record given and would therefore be the same for the 

 second interval of time. 



IMPORTANT DIFFERENTIAL CRITERIA 



The following criteria have been found of value in the dififerentiation 

 of the various species: (i) Macroscopic characters, including rapidity 

 of growth, color of aerial and submerged mycelium, character of aerial 

 mycelium such as to texture, etc., staining of the agar, decoloration of 

 the agar, the comparative rate of growth between the aerial and sub- 

 merged mycelium, especially when the submerged mycelium is colored 

 and markedly in advance of the aerial; (2) microscopic characters, such 

 as septation, branching, size and color of hyphae, clamp connections, 

 polymorphism in spore formation, etc. A few of the species of Polypora- 

 ceae examined by the writers have in addition to the usual basidiospores 

 other spore forms variously known as conidia, oidia, chlamydospores, etc. 

 These various nonbasidiosporic forms may be divided into two general 

 groups, spores which are borne on the aerial hyphae and the so-called 

 spores which are borne on the submerged hyphae, often referred to as 

 chlamydospores. The latter have been found by the writers to be more 

 widely distributed in the Polyporaceae than the aerial spores and their 

 presence and characters as well as those of the aerial should always be 

 noted, since they are of great diagnostic value. 



It will be noted from the tables that certain fungi have colorless or 

 white aerial mycelium throughout on certain agars, while others have 

 colored depending upon the agar used. Such color differences are very 

 important, since they are usually constant for a given species on a given 

 agar. 



In some species of the fungi examined the submerged mycelium in 

 certain media is constantly colored, while in other species, whether the 

 submerged mycelium is colored or colorless, seems to depend upon certain 

 environmental factors, such as the amount of moisture present in the 

 medium or the acidity or alkalinity of the medium. 



