144 A. E. HILTON ON SPORANGIAL CHARACTERS OF MYCETOZOA 



doubtedly true that simple combinations of these " well-known 

 forces " lead to " complicated and apparently purposeful results," 

 but the supposed " purpose " always ends in simple spore-pro- 

 duction, however intricate the processes may seem to be. 



In the case of sporangia which are not sessile, the formation 

 of a stalk becomes more intelligible when we realise the essential 

 fact that stalk and sporangium develop concurrently as the 

 dual result of one and the same process. A good illustration of 

 this is furnished by the well-known species Comatricha nigra, 

 the successive phases of which are indicated by the following 

 figures : 



cy Gl 



B 



A. Cushion of watery plasm on surface of dead wood, from 



interior of which it has just emerged. 



B. Plasm more erect, with base of stalk visible at centre. 



C. Stalk lengthening upward. Plasm still adhering to base. 



D. Further extension of stalk. Plasm detached from base, and 



being drawn upward by rounding action of surface tension. 



E. Stalk at full length. Plasm rounded by surface tension. 



Interior secretions from plasm forming capillitium branch- 

 ing from summit of stalk. Capillitium partly visible. 

 Sporangium becoming opaque. 



F. Final shape of sporangium. Spherical form modified by 



capillitium and effects of desiccation. 

 This is a fair example of the general process of stalk-formation 

 throughout the group, due allowance being made for specific 

 differences in the plasm, especially of those species containing 



