628 THE GENUS HYSTERIUM AND SOME OF ITS ALLIES. 
Again it must be remembered that the classification of the genus 
Hysterium must’ be as yet provisionary, not being based at all 
upon the only real test of a true species, viz., the propagation of 
its kind. But before we can attempt the true physiological clas- 
sification of such forms, we must have some sort of division of 
them that we may know what we are talking about. In this point L 
of view it is evident that we want to name as many forms as pos- 
sible to avoid confusion, and that two different forms should not 
receive the same name unless the observer is very certain as to 
their identity. To explain my meaning more fully I will take the — 
case of one of the commonest forms among the Ascomycetes, viz., 
Hysterium pulicare Pers. The description of this species, as given 
` by Persoon, Fries and the older mycologists, is entirely insufficient 
to enable us to identify it, and we must have recourse to authentic 
specimens to know positively which form the older authors placed 
under this head. The spores shown in fig. a of plate 11 were 
drawn from a specimen in the Schweinitz herbarium received from 
Fries as a type specimen. Another specimen from Fries, marked 
B. lenticulare has the same kind of spores. A specimen from the 
Scleromycetes Suicie in Mr. Ravenel’s herbarium has somewhat 
larger spores which are obovate, triseptate and very dark brown. 
Duby states as the result of the examination of authentic speci- 
mens that the spores of H. pulicare are oblong, two or three times 
longer than wide, triseptate, clear brown, or with the terminal lo- 
culi colorless. When young the spores are 1-septate and hyaline. 
Corda figures the spores in like manner. On the other hand, I 
find in one specimen named by Kunze, and in specimens named by 
Berkeley, Curtis and Ravenel, that the spores are much larger, 
darker, more opake, with longitudinal septa and obovate or pyti- 
form, in short, like the fruit of H. elongatum. (Pl. 11, fig. k). The 
authors last named consider the above as belonging to H. pulicare 
for the reason that in one perithecium, resembling those of that 
species, they find spores varying from the short, colorless, unisep- 
tate form, to those described above. It is of course possible, 
and perhaps not improbable, that the large cellular spores are the 
fully developed fruit, but on the principles stated above (as I find 
in the majority of authentic specimens that all the spores present 
an equal development and yet have a simpler form), I prefer to 
consider that form as the perfect type and refer the others to H. 
elongatum. 
