ACKASIEAE 161 



and M. amyli, have a course of life that approaches that of 

 Mycetozoa very closely. 



The convincing resemblance that the mycetozoan plas- 

 modium bears to rhizopods needs no emphasis. The absence 

 of mention of chromidia in most accounts of Mycetozoa 

 might be regarded as pointing to an essential difference, but 

 chromidial features which I found in Didymium difforme 

 (Part IV) remove some of this seeming distinction. 



Of all Sporozoa, the Haplosporidia ; that heterogeneous 

 group founded by Caullery and Mesnil in 1899, are the most 

 likely to furnish examples of kinship to mycetozoa. One 

 haplosporidian, Schewiokovella schmeili, a parasite of cope- 

 pods, has an unsporozoan character in the presence of a 

 contractile vacuole, and a mycetozoan character in that the 

 young animals sometimes fuse into a plasmodium, which 

 becomes encysted and subdivides into spores. Another 

 Haplosporidian, Ehinosporidium kinealyi, is the cause of 

 infective tumours in the nasal fossa and other parts of the 

 human body. In this species also, as is shown in Part IV, 

 there is evidence of a contractile vacuole at one stage, while 

 at another stage the parasite assumes a chromidial or even 

 a plasson state. 



From some simple alga or alga-like fungus such as 

 Aphragmium (p. 35) may have evolved both Acrasieae and 

 Mycetozoa. 



11 



