THE MYCETOZOA 



57 



region often gives rise to a spongy base to the aethalium, to 

 which the name hypothallus has been loosely applied, though the 

 structure is as distinct from the true hypothallus as is any other 

 part of the supporting substance. 



Many Mycetozoa forming aethalia are closely allied to species 

 with discrete sporangia. Thus Fuligo is an aetlialioid form of 



FIG. 16. 



Aethalium of Fuligo septica. a, part of a ripe aethalium in section, showing the cortical 

 fayer, x 1. 6, part of a section of the developing aethalium, showing the separate convoluted 

 tubular sporangia of which the aethalium is composed, x about 390. (After de Bary, 2.) 



Physarum, Spumaria of Didymium-, and species in which the 

 sporangia are usually distinct may assume an aethalioid form, as in 

 the "confluent" variety of Stemonitis fusca. 



In some species the plasmodium does not become rounded off into 

 distinct and symmetrical spor- 

 angia in the spore-producing 

 stage, but retains a diffused 

 and lobate form. In other re- 

 spects maturation proceeds as 

 in ordinary sporangia. These 

 bodies are known as plas- 

 modiocarps (Fig. 17). Aethalia 

 appear to be formed by the 

 fusion of sporangia, while 

 plasmodiocarps are sporangia 

 incompletely segregated. 



Plasmodiocarps are characteristic of some genera (Licea), but 

 frequently occur together with completely -formed sporangia in 

 the same species of others. 



THE EXOSPOREAE. 



The genus Ceratiomyxa (formerly known as Ceratium), the single 

 representative of the Exosporeae, differs from the Endosporeae 



FIG. 17. 



The plasmodiocarp form of Didymiitm f/usum. 

 X 15. (After A. Lister, 18.) 



