1066 The American Naturaltst. [ December.. 
forced a step farther back and take place within the ascus, giving 
to it an indefinitely polysporic appearance. Conidia of this type 
usually increase freely by yeast-like budding, like those of the 
Ustilaginez ; and, excepting those of the Taphrinz, they usually 
develop readily, under suitable conditions, into filaments. The 
less specialized conidiophores have their conidia scattered over 
their entire length, and a gradual advance may be traced from 
this form to those whose conidia are wholly restricted to their tips. 
Besides occurring separately, conidiophores are found grouped 
into dense clusters, such as have been described under the name 
Coremium, or into more extensive, compact “stromata.” In sim- 
pler cases the surfaces of these stromata are flat; but they may 
be ridged or folded, and a fold may increase in depth until its 
edges meet, and a closed cavity is the result. Such a series may 
be traced in Nectria and its allied genera of the Hypocreacee. 
Closed conidial fruits which may be supposed to have originated in 
this way are very common among the Ascomycetes, and have long 
been known under the name pycnidia. They are known among 
the Basidiomycetes only in the Uredineze and the new Tremella- 
ceous genus Craterocella. In their development pycnidia present 
two types. They originate by the interweaving of previously 
formed threads (symphyogenic), or by the fusion of newly formed 
threads into a parenchymatous mass (meristogenic). Within the 
cavity of the pycnidium spores may be formed from all the cells 
or only from the terminal cells of the spore threads, just as in the case 
of free conidiophores. Two distinct forms of conidia may be 
borne on the same conidiophore or within the same pycnidium; or 
they may be separated, and so lead to distinct conidial or pycni- 
dial forms on the same plant. 
A fruit form very common among the Ascomycetes and the 
Uredinez is that which has been known as the spermogonium, 
on account of its supposed sexual nature. This organ is structur- 
ally like the pycnidium; but the spore-like bodies developed in 
its cavity have been supposed, chiefly from the analogy of the 
spermatia of the Floridez, on account of their minute size and 
the fact that they had never been seen to germinate, to be male 
sexual elements. But Brefeld and his pupil, Möller, have suc- 


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