The Myxomycetes of Eastern Iowa. 103 



charm into one wide-spread, dusty field of flying spores. Or, 

 to be more exact, whatever the position ultimately assumed 

 the Plasmodium soon becomes quiescent, takes on definite 

 and ultimate shape which varies greatly, almost for each 

 species. Thus it may simply form a flat cake-like mass, 

 (Bthalium^ internally divided into an indefinite number of ill- 

 defined spore-cases (sporangia) ; or the plasmodium may take 

 the form of a simple net, plasmodiocai'p, whose cords stand 

 out like swollen veins, whose meshes vary both in form and 

 size; or more commonly the whole protoplasmic mass breaks 

 up into little spheroidal heaps which may be sessile directly on 

 the substratum, or may be lifted up on tiny stems (stipitate), 

 which rest in turn upon a common sheet-like film spreading 

 beneath them all, the hypoihallus. In any case, each differ- 

 entiated portion of the plasmodium, portion poorly or well 

 defined, elongate, net-Hke, spheroidal, elliptical or of whatever 

 shape, becomes at length a sporangium, spore-case, recepta- 

 cle for the development and temporary preservation of the 

 spores. 1 The Slime-moulds were formerly classed with the 

 gasteromycetous fungi (puff-balls), and in description of their 

 fruiting phase the terms applicable to the description of a puff- 

 ball, are still employed, although it will be understood that the 

 structures described are not in the two cases homologous; 

 only analogous. The sporangium of the Slime-mould, exhibits 

 usually a distinct ^£j;7Vf/«/7^ or outer limiting wall which is at 

 first continuous, enclosing the spores and their attendant 

 machinery, but at length ruptures, irregularl}^ as a rule, and 

 so suffers its contents to escape. The peridium may be 

 double, varies in texture, color, persistence and so forth, as 

 will be more fully set forth in the several specific descriptions. 

 The peridium blends with the hypothallus below when such 

 structure is recognizable, either directly, when the sporangium 

 is sessile, or by the intervention of a stipe. The stipe may be 

 hollow, may contain coloring matter of some sort, or may 

 even contain peculiar spore-like cells or spores; is often fur- 



I See however Ce?'a/<'(?;«^xa, p. 114 following. 



