THE MYXOMYCETES OF PICTOU COUNTY. MOORE. 177 



M ij.vogastres with the limits originally assigned it that is, us 

 co-extensive with the Endosporece of Rostafinski's classification 

 arid narrower than the Myxoyasteres of Schroter which is a 

 synonym of Rostafinski's Mycetozoa. 



Lister, on the other hand, accepts the group Mycetozoa as 

 established by Rostafinski, hut excludes Dictyostelium, one of 

 the Acrasiece, which had been admitted by the latter evidently 

 through a misapprehension of the nature of its plasmodium. 

 " We have thus," he says, " a clearly defined group of organ- 

 isms separated from all others by the following combination of 

 characters. A spore provided with a spore wall produces on 

 germination an amoeboid swarm cell which soon acquires a 

 flagellum. The swarm cells multiply by division and subse- 

 quently coalesce to form a plasmodium which exhibits a rythmic 

 streaming. The plasmodium gives rise to fruits which consist 

 of supporting structures and spores. In the Endosporece these 

 have the form of sporangia each having a wall within which the 

 free spores are developed. A capillitium or system of threads, 

 forming a scaffolding among the spores is present in most 

 genera. In the Exospcrece the fruits consist of sporophores 

 bearing numerous spores on their surface." (A monograph of 

 the Mycetozoa, p. 2.) 



Macbride in his North American Slime Moulds (1899), 

 uses the term " Myomycetes (Link) de Bary," as a general 

 title, but includes in the group such forms as Plasmodiophora 

 which, as has been said, were excluded by de Bary in his treat- 

 ment of the group as being of doubtful affinity. As> thus limited, 

 the group embraces the Phytomyxinse and Myxogasteres of 

 Schroeter's system. 



Macbride groups the Myxomycetes as thus defined into three 

 main divisions or sub-classes : 



A. Parasitic in the cells of living plants. 



Sub-class. Phytomyxinae. 



