Opalina. 343 
said to preceede the formation of the infection cysts in the rectum 
of the frog; the complete disappearance of the refractive spherules 
before the formation of the infection cysts; the presence of always 
two and only two chromatin spheres in the nuclei before the forma- 
tion of the infection cysts, and their extrusion, one before encyst- 
ment, and one afterwards in the water or in the rectum of the 
tadpole (The definitiness of these phenomena seems to me uncertain); 
the presence of a double number of chromosomes in the sexual 
nuclei, 24 instead of 12 for O. ranaruwm and O. dimidiaia; isogamous 
copulation ; encystment following copulation (This seems to me 
doubtful); his interpretation of certain phenomena as abnormal 
budding (probably heterogamous copulation); his statement that the 
refractive spherules are homogenous; his belief that Opalina is related 
to the Plasmadroma rather than the Ciliophora; and his belief that 
all healthy frogs contain Opalinas.| 
Dosent (1907) observed O. ranarum and says he “confirms 
fully” NeresHErMer’s description of the nuclear phenomena preceeding 
encystment, i. e., “(1) formation of chromidia, (2) synthesis of fresh, 
nuclei from these chromidia, (3) reduction of chromatin and (4) en- 
cystment” [(1) and (2) I have not succeeded in finding in O. ranarum, 
or in any multinucleated Opalina; they do not occur in O. intestinalis 
or O. caudata: (3) seems to have no connection with true “reduction”. 
He observed and interprets as degenerative 1) the irregular divi- 
sions preceeding encystment [described by TOnnicEs for O. ranarum; 
see my Text Fig. III, page 241]; 2) the loss of cilia from animals 
kept “some days” outside the host; 3) the presence of refractive 
spherules in the cytoplasm, which “ultimately run together forming 
large masses lying in the cells” [the refractive spherules are, of 
course, present in normal Opalinas; I have never seen them fused 
to form large masses]; 4) nuclear degeneration accompanied by amitotic 
division, equal or unequal: the degenerating nuclei are said to 
extrude their chromatin in the form of chromidia and entirely dis- 
appear; “as a rule most of this chromatin is cast out of the organism, 
which then dies and breaks up, but occassionally only a part of the 
chromatin in cast out and perishes, the remaining granules” running 
together to form “two nuclei, consisting of solid chromatin”, which 
“then approach one another and fuse”. 
Mercaur (1907 a) a preliminary notice of the present paper. 
Hartmann (1907) accepts NeresHermer’s (1907) conclusion that 
Opalina should be removed from the Ciliophora to the Plasmodroma, 
but does not assign it a definite position in the latter group. 
