INTRODUCTORY 5 



sporangium, spore-case, receptacle for the development and tempo- 

 rary preservation of the spores. ^ 



The slime-moulds were formerly classed with the gasteromycetous 

 fungi, pufiE-balls, and in description of their fruiting phase the terms 

 applicable to the de^scription of a puff-ball are still employed, al- 

 though it will be understood that the structures described are not in 

 the two cases homologous; analogous only. The sporangium of the 

 slime-mould exhibits usually a distinct peridiunij or outer limiting 

 wall, which is at first continuous, enclosing the spores and their at- 

 tendant machinery, but at length ruptures, irregularly as a rule, and 

 so suffers the 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 recog- 

 nizable, either directly, when the sporangium is sessile, or by the 

 intervention of a stipe. The stipe may be hollow, may contain color- 

 ing matter of some sort, or may even contain peculiar spore-like cells 

 or spores ; is often furrowed, and in some cases shows a disposition to 

 unite or blend with the stalks of neighboring sporangia. In many 

 cases the stipe is continued upward, more or less definitely into the 

 cavity of the sporangium, and there forms the columellaj sometimes 

 simple and rounded, like the analogous structure in the Mucores, 

 sometimes as in Cornatricha, branching again and again in wonderful 

 richness and complexity. 



Each sporangium is at maturity filled with numerous unicellular 

 spores. These are usually spherical, sometimes flattened at various 

 points by mutual contact; they are of various colors, more commonly 

 yellow or violet brown, are sometimes smooth (?), but generally 

 roughened either by the presence of minute warts, or spines, or by 

 the occurence of more or less strongly elevated bands dividing retic- 

 ulately the entire surface. The spores are in all cases small 3-20/*, 

 and reveal their surface characters only under the most excellent 

 lenses. 



Associated with the spores in the sporangium occurs the capillitium. 

 This consists of most delicate thread- or hair-like elements, offering 



^ See, however, Ceratiomyxa, p. 18, following. 



