THE MYCETOZOA 39 



several directions ; among others with unicellular algae, the 

 Mycetozoa and such forms as Actinophrys. Of these alliances, that 

 with the algae is the least satisfactorily established by Cienkowski, 

 but that between the " Monadina " and the Mycetozoa has been 

 generally accepted by de Bary and later writers. 



Zopf (24) considerably enlarged the "Monadina " of Cienkowski, 

 and in 1887 included them in the Mycetozoa, distinguishing the 

 forms here included, as the Eu-mycetozoa. This course is open to 

 objection on several grounds. The "Monadina" of Zopf appear 

 to be still a very heterogeneous collection of forms, and their 

 inclusion in the Mycetozoa tends to obscure the well-marked features 

 of this group. Further, though the affinity of some of the 

 Monadina with the Mycetozoa seems probable, others are as closely 

 connected with the Heliozoa, in which class the majority of them 

 are, in fact, included by Biitschli (4). 1 



Hence the limits of the Mycetozoa, as here understood, are the 

 same as those drawn by de Bary. They include (1) the Sorophora 

 of Zopf (the Acrasiae of Van Tieghem) ; (2) the remainder, and 

 great majority of the species, for which de Bary retained the old 

 name of Myxomycetes. The only objection to retaining this name 

 is that it is generally used as synonymous with Mycetozoa. The 

 term Eu-mycetozoa would have been preferable, but it is used by 

 Zopf to include the Sorophora. Delage and Herouard have applied 

 the name Euplasmodida to the higher group, a course which avoids 

 all confusion, and emphasises one of the chief characters which dis- 

 tinguishes it from the Sorophora. 



In a more recent work (25) Zopf has included the Labyrinth uleae as 

 a sub-order of the Sorophora. He has shown that the singular network 

 described by Cienkowski in Labyrinthula, by which the individuals are 

 united, is pseudopodial in nature, and regards the whole colony as forming 

 a body of the nature of a plasmodiuni, to which he applies the name 

 thread-plasmodium. There appears to be no evidence, however, that the 

 term plasmodiuni is any more applicable to the colony of Labyrinthula 

 than it is to those, e.y., of Mikrogromia, or the colonial Radiolaria. The 

 actively parasitic habit, the entirely aquatic life, the defined shape of the 

 members of the colony, and the absence of any proof that it is formed 

 by fusion of individuals, keep Labyrinthula distinct from forms hitherto 

 included in the Sorophora. Penard (20a) has recently extended our know- 

 ledge of Chlamydomyxa, showing that the " oat-shaped corpuscles " are 

 not nucleated, and therefore not comparable with the fusiform bodies of 

 Labyrinthula ; and also that the contents of the cysts escape as flagellate 

 zoospores. Penard finds a great analogy between this genus and the 



1 Whatever position is ultimately assigned to the " Monadina " of Cienkowski 

 and Zopf, it is desirable that this name for them should fall into disuse, for it is now 

 applied in zoological works to the simpler members of the Flagellata, in which the 

 flagellate and not the amoeboid stage is predominant in the life-history. 



