1064 The American Naturalist. [December, 
In the study of more than 400 Ascomycetes there has been 
found the greatest diversity in the time of the appearance of the 
ascus in the fruit body, and in its relations to the tissue of threads 
composing that body. In some cases the asci and the inter- 
mingled sterile threads, or paraphyses, arise as branches of the 
same hyphæ; or, again, the two may rise from separate hyphal 
systems which are differentiated early and remain structurally 
distinct. This distinction is never seen in the Basidiomycetes 
and is not to be expected, since none of their ancestral Phycomy- 
cetous forms show any such differentiation as has been described in 
Rhizopus and Mortierella, which are believed to represent ancestral 
forms of the Ascomycetes. Brefeld points out that it is this dif- 
ferentiation of fertile and sterile threads which has given rise to 
the doctrine of the sexuality of the Ascomycetes of which DeBary 
has been the especial champion. He contends elaborately and with 
the strongest emphasis that there exists no proof whatever that the 
so-called “ ascogonium” and “ pollinodium ” observed in certain’ 
Carpoasci are of any sexual significance. This view, he main- 
tains, has been reached deductively, and not inductively ; by infer- 
ence, and not by proof. The analogy of the sexual organs of the 
Florideze has exerted a strong influence on the interpretation of 
the significance of the structures in question and of the so-called 
“spermatia,” to be discussed later; yet the Florideæ and the 
Ascomycetes are as little related as any two groups of Thallo- 
phytes. The fusion of the initial fertile filament with one or more of 
_ the surrounding sterile filaments has no more significanc than any 
of the hyphal fusions, so common among fungi. It is quite as 
reasonable to suppose that, in the great number of forms in which 
this early differentiation is not observed, it has become obscured 
or lost in the bewildering tangle of hyphæ, as that typically 
. sexual fungi have lost their sexual organs by abortion. 
Two fungi, Thelebolus and Ascoidea, have been mentioned as 
having ascus-like sporangia, and as holding an intermediate place 
between the Phycomycetes and the true Ascomycetes. With 
these should be mentioned a third genus, Protomyces. This 
genus has been recognized as related to the Ustilaginez, since its 
spores are developed from the hyphz in much the same manner 

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