8 GENERA OF FUNGI 



of relative merits is possible, but for definiteness and convenience the Sac- 

 cardian arrangement appears much more preferable. Moreover, since all 

 three criteria must be employed in any system, it is a distinct advantage to 

 first utilize the one most clear-cut and easily determined, and last that which 

 presents the most difficulty. This is the sequence followed in Saccardo's 

 spore sections, in which the spore plays the primary role, the perithecium 

 comes next, and the stroma last. Even Winter, who used the stroma for his 

 subdivisions of the Sphaerialcs, emphasized the undesirability of placing too 

 much stress upon this structure. 



In general, the usage with respect to the spore is so definite and uni- 

 versal as to require little comment. In spite of some intergrades, as well as 

 occasional variation within a species, the color and septation of the spore 

 are generally dependable criteria in the Ascomycetcs and Deuteromycetes. 

 The presence, position, number and form of spore appendages are also regu- 

 larly utilized, but with some exceptions. With respect to other spore charac- 

 ters, the practice has been far from uniform. Thus with regard to the 

 epispore, genera have been separated on the nature of the markings in some 

 groups and not in others. It may prove best not to assign this criterion 

 generic value, though there is no question of its convenience, especially in 

 Moniliales, where criteria are often at a premium. 



In the present treatment, several spore characters recently employed by 

 some mycologists are not considered to be of generic value. These are 

 unequal cells in didymospores and the form of the cells in phragmospores. 

 A third feature, that of the breaking apart of the cells in scolecospores, is 

 likewise regarded as too variable and unimportant to be utilized. Theissen 

 and Sydow have made regular use of unequal spore-cells, but an examina- 

 tion of the genera erected upon this discloses its weakness. This is the wide 

 range of variation within a genus and often in the same species, while in 

 more than one instance genera based upon equal spore-cells contain species 

 with as much inequality as some in those genera stamped with this character. 

 An examination of all the species concerned in the eight examples of generic 

 subdivision on this basis in "Die Dothideales" demonstrates that this is 

 entirely unwarranted, a fact not entirely unrealized by the authors in the 

 statement made under Placostronia (p. 407) : "The inequality of the spore- 

 cells is not so sharply marked, as in Coccoides, Coccochorella, etc., that this 

 species must be generically segregated." The same authors have also based 

 new genera upon both 3- and 4-celled spores, but the unlimited possibilities 

 in this direction render comment unnecessary. 



The scolecospore presents some problems peculiar to itself with respect 

 to form, septation and color. Dark scolecospores are rare, but a tinge of 

 color is less infrequent ; septation is highly variable, sometimes in the same 

 species, and is seldom if ever to be depended upon. While the extremes of 

 the two characteristic forms, acicular and filiform, are distinctive, they 

 vary and intergrade too much to render them serviceable as a rule. The 

 major difficulty lies in a definite distinction between the phragmospore and 



