28 



MYCETOZOA AND BELATED ORGANISMS 



Fig. 4. Myxogastrales. (A, B) Fuligo septica (L.) Gmel. (A) Habit drawing. (B) 

 Capillitium and spores. (C, D) Physarum nutans Pers. (C) Sporangia. (D) Capillitium. 

 (E) Dictydium cancellatum (Batsch) Macbr., showing persistent ribs of sporangium 

 wall. (After Lister: A Monograph of the Mycetozoa, London, The British Museum.) 



Mention should be made of Stemoniiis, with purple or rust-brown 

 spores, clustered, stalked fruit bodies with the stalk extending upward 

 as an axial strand (columella) from which branch off the capillitial threads 

 which are combined into a loose network that is surrounded by an eva- 

 nescent peridium. Physarum has clustered, separate or compacted, sessile 

 or stalked, lime-encrusted sporangia whose capillitial threads are ex- 

 panded here and there and filled with lime granules. Fuligo has a similar 

 capillitium but the spore fruits are united into a single large convolute 

 "aethalium." This is one of the largest of the Slime Molds. In Dictydium 

 the stalked sporangium has no internal capillitium but when the peridium 

 disappears it leaves numerous longitudinal ribs that run from base to 

 apex like the Hues of the meridians on the globe. Arcyria and Trichia have 

 sessile or stalked fruits. The capillitium lacks a columella and consists of 

 a tangle of tubular threads with characteristic thickenings such as spines, 

 warts, rings, etc. (Fig. 4.) 



The fructifications of Slime Molds may be found on rotten logs or 

 stumps, on sawdust, leaves, beams in moist cellars, and frequently on 

 blades of grass or other vegetation in lawns. Very dry habitats do not 

 favor their occurrence. In moist weather the plasmodia may be found 

 creeping about on the surface of, or emerging from, the various substrata 

 within which they develop. It is possible to grow some species in pure 

 cultures, from the spores to the maturity of the fructifications. 



