335 
classed with the Rhizopoda, and the only certainly known 
representative of the true Actinophrys. I should prefer 
to transfer this organism to the Monera, and to place it 
between Yampyrella and Myxastrum. The peculiar very 
large contractile vesicle of this Protiston would then have 
to be considered as a mere vacuole. But, as in spite of the 
Actinophrys sol being very common, we still continue to know 
nothing certain of its reproduction and development, its posi- 
tion among the Monera must at present still remain doubt- 
ful. The resting condition of Actinophrys sol observed by 
Cienkowski (1. c., p. 227), renders its position among the 
Monera still more probable. It might probably be in future 
advisable, also, to add to the Monera, besides the true Actino- 
phrys sol (Elirenb.), a number of nearly allied Actinophrys- 
like Protista, such as Trichodiscus and Plagioplirys. 1 The 
newly described Clathrulina of Cienkowski, which I have 
also observed near Jena, I consider a true Rhizopod, and 
place it with the Monothalainia, among the Acyttaria. 2 
II. Monera and Flagellata. 
Among the various forms of Monera, the zoospores of Pro- 
tomonas and Protomyxa show the greatest resemblance to the 
simplest forms of Flagellata. The latter are distinguished by 
the presence of nuclei and of envelopes. The developed and 
freely moving Flagellatum is never a Gymnocytode, as all 
Monera are in their freely moving condition. 
III. Monera and Labyrinthulea. 
Among the Monera, Myxastrum, in its reproductive state, 
strongly reminds us of Labyrinthula. But the individual 
Plastides of the latter are always nucleated, and thus are true 
cells, while the Monera never possess nuclei. 
IY. Monera and Diatomacece. 
The spindle-shaped siliceous-shelled spores of Myxas- 
trum remind us of the Diatomaceae also, as they do of the 
1 Aclinospharium Eichhornii (Stein), which as Actinophrys Eichhornii, 
Ehrenb., not Kolliker, is still generally confounded with the true Actino- 
phrys sol (Ehrenberg; Actinophrys Eichhornii, Kolliker), is very widely 
different from it. In Actinophrys sol the entire protoplasm body is, as in 
the Monera, structureless, while in Actinosphcerium Eichhornii we have a true 
Rhizopod, in which nucleus-containing cells have already differentiated 
themselves in the outer substance of the body. 
2 Cienkowski, “ Ueber die Clathrulina, eine neue Actinophrven-Gattung 
‘ Archiv fur mikrosk. Anatomie,’ 1867, pp. 311, 316, Taf. xvili. 
