[Vol. 2 

 750 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



tions by giving spore characters, dimensions of basidia, 

 cystidia, and hyphae, and the presence or absence of clamp 

 connections. Such additional characters may often be ob- 

 tained quickly by microscopic examination of a portion of the 

 fructification which has been teased out and crushed down 

 in dilute potassium hydrate solution; by these helpful addi- 

 tional characters, some species may be recognized with reason- 

 able accuracy, but there are comparatively few such species. 

 Structure in section of the fructification affords important 

 characters for the identification of resupinate species. In 

 practical work with these species, a microscopical mount of 

 a sectional preparation of a type specimen is the next best 

 thing for purposes of comparison to having the type itself. 



My method of determining a resupinate specimen is to ob- 

 serve closely its general habit and characters, such as con- 

 sistency, adnation, thickness, surface, margin, substratum, 

 and color. Color is an important character when given in 

 terms of an adequate color standard. The color which the 

 specimens retain in drying is often the only color character 

 available; it is more constant, fortunately, than is com- 

 monly appreciated, for it has to be the color factor in the 

 comparison of herbarium specimens. The preliminary ob- 

 servation may suggest that the species is one of several of 

 somewhat similar habit which may be of the same genus or 

 of various genera. The sectional preparations, which are 

 now made, may present (a) a uniform, homogeneous arrange- 

 ment of similar hyphae from substratum to hymenium, (h) 

 dissimilar hyphae or organs distributed uniformly through- 

 out the whole fructification, (c) a layered, heterogeneous ar- 

 rangement of various types with the layers more or less 

 sharply differentiated from one another, (d) a stratose ar- 

 rangement having the first stratum extend from the sub- 

 stratum to the upper surface of the first hymenium, the 

 second stratum a repetition of the first and borne on the first, 

 and so on. Under a there are characteristic varieties of struc- 

 ture, constant for each species, such as all the hyphae in erect 

 position extending from substratum to hymenial surface, or 

 all interwoven, or all procumbent, and there are also constant 



