KEY TO THE CLASSES OF HIGHER FUNGI 197 



Coloring 



In the majority the vegetative mycelium is colorless and that is true 

 of the reproductive structures in many cases. In rhizomorphs and the 

 outer layer of cells of sclerotia and sometimes in individual hyphae the 

 color may be dark. This color seems to reside in the cell wall and is prob- 

 ably related chemically to melanin. Some fungi produce pigments in the 

 interior of the hyphae. These may be soluble in various solvents and are 

 sometimes variable in color depending upon the chemical reaction. Thus 

 a Fusarium studied by the author (1904) and parasitic on Sesamum 

 orientale L. produces a red- or violet-colored pigment that turns blue 

 when the surrounding medium becomes alkaline. It is soluble in acids 

 and the red form is soluble in solutions of their salts. Litmus is the product 

 of the cells of one of the lichen-producing fungi, as is orcein. Some hyphae 

 cause the coloration of the substratum in which they are growing. Thus 

 wood in which Chlorociboria aeruginosa (Fr.) Seaver is growing takes on 

 a green color, due to a pigment secreted by the mycelium. The repro- 

 ductive structures are in the majority of cases colored, the pigments 

 in some being within the cell (e.g., the bright red color of the hymenium 

 of some Pezizales), in others in the cell wall. The latter is mostly the case 

 with the light to dark brown or almost black coloration found in the 

 majority of apothecia and perithecia and in the teliospores of Rusts and 

 Smuts, the spore fruits of Tremellales, Auriculariales, etc. The fungus 

 pigments, especially those occurring in the lichen-producing fungi, have 

 been studied by various authors but no really comprehensive modern 

 study has been made of the subject taking advantage of the more recent 

 investigations in organic chemistry. 



Nomenclature 



The Higher Fungi were called by Charles E. Bessey (1907) the Phylum 

 Carpomyceteae, i.e., fruit-producing fungi, in reference to the production 

 of spore fruits in this phylum. The name Eumyceteae is often applied to 

 this group but is here discarded in view of the fact that it has also been 

 applied to include all the filamentous fungi in contrast to the nonfila- 

 mentous Mycetozoa, Chytridiales, etc. The Higher Fungi are divided into 

 several classes whose distinctions are based on the type of the ultimate 

 reproductive cells of the spore fruits. 



Key to the Classes of Higher Fungi 



The ultimate reproductive cells of the spore fruit are ascospores, produced mostly 

 eight in number within the cell called an ascus, which starts out as a di- 

 caryon cell in which the nuclei fuse, the resultant diploid nucleus then 

 dividing meiotically until usually eight nuclei are produced, around which 

 the ascospores are developed. Over 42,000 species have been described. 



Class Ascomyceteae 



