42 The Mycetozoa.) and 



forms a sporangium. In other cases the plasmodium 

 begins its transformation as a whole, and breaks up into 

 sporangia as the process advances. 



Comatricha and Craterium appear to be cases of the 

 former mode of procedure ; Stemonitis of the second. Thus 

 in Comatricha the plasmodium emerges in separate centre?, 

 like small conical hillocks on the wood. These grow 

 upward, and as they approach maturity the upper part of 

 the protoplasm draws all the lower part after it, except so 

 much as goes to form the pedicel and hypothallus, or foot. 



In Stemonitis, on the contrary, the plasmodium gathers 

 itself together in a lump or mass, and first shows signs of 

 dividing up by the appearance of papillae on the surface ; 

 then at points corresponding with the papillae, dark-coloured 

 stems grow upwards in the gelatinous mass. Around 

 these stems, portions of the adjoining protoplasm gather, 

 and separate vertically from their neighbouring parts ; and 

 again, before maturity, the lower portion of the protoplasm 

 around each column moves upwards, leaving only the 

 delicate stalk which supports the arborescent sporangium. 

 Fig. 10 will explain these steps in development. 



It would seem as if the sporangium forms were the most 

 highly developed, and the plasmodiocarp form the more 

 rudimentary. We suppose that in the matter of advantage 

 to the organism there must be something to be said for 

 and against each form, for the plasmodiocarp must expend 

 less material on perishable walls and stalks, and, on the 

 other hand, be less open to the atmospheric influences ; 

 whereas the opposite in each respect must apply to 



