224 
F. Cavers. 
phase, and one rounded off, in cell on right division into zoospores; 2, infection 
of a filament by zoospores, amoebula and heliozooid phase. C, Colpodellapugnax 
Zopf: 1, an individual attacking a Chlamydomonas ; 2, 3, after destroying the 
host, the parasite escapes in amoeboid form, but later divides into flagellate 
individuals. D, Protomonas sp. Cienk.: 1,2, 3, different forms of zoospore ; 4, 5, 
amoebulae. E, Diplophysalis stagnalis Zopf, showing formation of endogenous 
cyst with spinose wall. F, Pseudosporidium brassanium Zopf : I, amoebula ; 2, cyst; 
3, zoospore. G, Ectobiella plateaui de Bruyne : 1, parasite sending a pseudo¬ 
podium into a diatom ; 2, zoospore. H, Diplophrys stercorea Cienk.: six individuals 
united by fine pseudopodia to form a loose plasmodium ; 2, zoospore. I, Biomyxa 
cometa Cienk. J, Arachnula impatient Cienk. K, Pontomyxa Jlava Tops, L, 
Boderia turneri Wright. M, Diplophrys (?) archeri Barker. N, Bursulla crystallina 
Sorokin: 1, stalked cyst; 2, rupture of cyst and escape of amoebulae. O, 
Mikrogromia socialis Hertw. and Lesser: 1, individual undergoing longitudinal 
division (transverse division also occurs in this organism) ; 2, escape of one 
individual as a Mikrogromia form ; 3, escape of one individual which later (4) 
becomes a zoospore ; 5, two individuals formed by division, as in 2, remaining 
attached to form a young colony. P, Ciliophrys infusionum Cienk.: 1, heliozooid 
form; 2, zoospore. Q, Vampyrellaspirogyrce Cienk.: 1, heliozooid phase ; 2, same 
attacking a Spirogyra cell ; 3, endogenous cyst in which division occurs ; 4, 
encysted individual divided into four amoebulae of which one is escaping. R, 
Vampyrellidium vagans Zopf: four heliozooid individuals of different ages in an 
Oscillatoria filament. S , LeptopJirys : \,L.vorax Zopf, heliozooid phase; 2, L. 
viilosa de Bruyne, amoeboid phase. T, Nuclearia delicatula Cienk., heliozooid 
phase. U, Monobia confluens Schneider, plasmodium of heliozooid individuals. 
V, Gloidium quadrifidum Sorokin : 1, amoeboid individual; 2, division into four. 
W, Gringo, filiformis Frenzel. X, Entcromyxa paludosa Cienk., with numerous short 
pseudopodia along the vermiform body. Y, Endyonema polymorpha Zopf, multi- 
nucleate individuals (or plasmodia ?) in an Oscillatoria filament. Z, Haplococcus 
sp. Zopf : 1, cyst, external view ; 2, optical section of cyst, showing three pits 
and division of contents. Lettering :— chlor., chloroplasts of algal filament; 
c.v., contractile vacuole ; fac., faecal vacuole ; nil., nucleus. 
It must be admitted that Zopf’s division of Proteomyxa into 
Zoosporeae and Azoosporeae leads to the separation of forms which 
differ in little or nothing more than the presence or absence of a 
flagellate phase. The life histories of several of the genera are 
very incompletely known, and it may he noted that recent investiga¬ 
tion of forms previously described as Azoosporeae has resulted in the 
discovery of a flagellate phase. Partly for convenience, partly 
because on the whole it would appear that the Zoosporeae include 
the more primitive forms of Proteomyxa, we shall take these first. 
What we may take as the typical life history of the simpler 
Proteomyxa, that is, those which approach most closely to the 
Pantostomatineae from which we assume the group to have arisen, 
and which indeed differ from such Pantostomatineae as Mastigamceba 
or Dimorpha only in the predominance of the amoeboid or heliozooid 
phase over the flagellate phase, is well seen in Pseudospom and its 
allies. In Pseudospom (Pig. 4, A, B) a cyst is formed which gives 
rise to a number of flagellulae, but these after reaching the host 
(species of algse or fungi) lose their flagella and become amoeboid 
and later heliozooid and finally producing a cyst. A curious feature 
in Pseudospora lindstedtii is a return to the flagellate condition at a 
late period, a flagellum being protruded just before encystment 
(Pig. 4, A, 5, 6). In P. volvocis, recently investigated by Miss 
Robertson (1905), the amoeboid or heliozooid form produces not 
only flagellulae (flagellate zoospores) but also numerous minute 
zoogametes which fuse in pairs, the zygote after a time losing its 
flagella and becoming amoeboid on reaching a Volvox colony into 
which it creeps. Except for the doubtful genus Chlatnydomyxn, this 
appears to be the only case in which sexual reproduction has been 
