146 A. E. HILTON ON SPORANGIAL CHARACTERS OF MYCETOZOA 



there is material of a cellulose nature ; and this must be re- 

 garded as an inevitable result of the metabolism of the plasm. 

 It is secreted in more perfect forms than the lime, and their 

 characteristics suggest that chemical as well as physical processes 

 are involved in their production. The minute spore-cases, of 

 different patterns, the slender threads of capillitia, often with 

 excessively jfine markings upon them, and sundry delicate mem- 

 branes, are all of this material ; and in combination with 

 albuminous refuse, also the result of metabolism, it enters into 

 the composition of cartilaginous stalks and sporangium walls. 

 Speaking generally, the lime deposits are coarser and conditional ; 

 the cellulose deposits inevitable and more specific. The cellulose 

 substance is in closer relation to the plasm ; but in the pro- 

 cesses of spore formation it is equally eliminated. 



The visible changes of colour, significant of interior rearrange- 

 ments, which occur while sporangia are forming are remarkable. 

 In the case of the familiar Comatricha nigra, for example, the 

 plasm, at the outset, is watery or milky white ; but as formation 

 proceeds, the colour of the sporangium successively changes to 

 pink, light red, coral red, black and purple-brown. A specimen 

 of Dictydiaethalium plumbeum, watched by me during develop- 

 ment, appeared on a piece of branch first as a chalk-white layer, 

 then contracted into a cushion of brilliant rose-pink, and finally 

 matured into an aethalium of a drab-clay colour. Plasmodia 

 of Lamproderma are watery-white or colourless, but developing 

 sporangia, after turning brown or reddish-brown and then black, 

 finally become iridescent, bronze-like, or shining like burnished 

 brass. We find, indeed, that if we take into account the whole 

 range of sporangial forms of Mycetozoa, all the prismatic colours 

 are represented more or less closely, but in unequal degree. It 

 is noticeable that green, blue and violet, though not absent, are 

 in very small proportion. This suggests a tendency to absorb 

 the light rays of the upper half of the spectrum. Conversely, the 

 colours of the lower half of the spectrum, yellow, orange and 

 red, are more in evidence ; yellow tints preponderating, with 



