GENUS BIOMYXA— BIOMTXA VAGANS. 283 



large, darkly defined granules, probably also oil-like in character. It con- 

 tains numerous minute contractile vesicles, commonly ranging from 0.002 

 mm. to double that size, and rarely reaching quadruple the same. They 

 are usually best seen and readily recognized by their characteristic move- 

 ments — slow enlargement, sudden collapse, and reappearance — along the 

 borders of the body and in the forks and nodal expansions of the pseudo- 

 pods. 



Rarely distinct vacuoles, independently of the contractile vesicles, and 

 much larger, are to be seen within the body mass of Biomyxa The round 

 holes which are often produced by the expansion and rupture of portions 

 of the protoplasm or by the closure of meshes in pseudopodal nets are to 

 be distinguished from the true vacuoles. 



Biomyxa vagans occurs of very variable size, and sometimes appears so 

 devoid of a definite centre, and without nucleus or other conspicuous 

 element, that I have supposed it was perhaps nothing more than a detached 

 fragment of Gromia. 



It has also been a question with me whether to regard it as a true 

 rhizopod or whether to view it as the plasmodium of a fungus.* In 

 structure and habit, so far as observed, it seems to accord with the latter 

 rather than with the former, though I have not detected a coalescence of 

 individuals in Biomyxa 



Cienkowski f has described several organisms, related with the latter, 

 of which he regards one as a 'fresh-water plasmodium,' while the others 

 are viewed as Rhizopods, under the names of Vampyrella vorax and Arach- 

 nula impatiens. 



The character of Vamp3 T rella has already been given; the diagnosis 

 of Arachnula is as follows: body naked, colorless, without nuclei, with one 

 or more contractile vacuoles; pseudopods but little branched, sometimes 

 anastomosing, usually springing by thick cords from any part of the surface 

 of the body. J 



In the same memoir, under the head of Naked Rhizopods, Cienkowski 



"The researches of Bary, Cienkowski, and others show that the spores of the little fungi of the 

 family Myxogastres emit flagellate cellules, which subsequently lose the flagellum and assume the 

 appearance and movements of Amoehas. By continued growth and coalescence, a number of the amoe- 

 boid cellules form together a branching and reticular layer of protoplasm, retamiug its motory power, 

 and named 'plasmodium' by Cienkowski. The plasmodium finally produces the spore-bearing fungus. 



t Archiv f. inikros. Anatomic, 15, 1876. 



I Ibidem, 27. 



