330 M. M. Mercatr 
frog’s rectum remain large in the spring and do not rapidly divide: 
the cysts in the tadpole hatch in either the intestine or the rectum, 
some within an hour after ingestion, some remainiug unhatched as 
much as seven days: the cysts never hatch in water but will hatch 
‘in the aqueous humor of the frog: experiments in artificial division 
were unsuccessful for the pieces, like the whole animals, died. 
Batprani (1887) refers at some length to the Opalinas; naming 
the hosts of the five species then known [Bombiator should have 
been included as a host of O. intestinalis (cf ZutLER 1877)|; diag- 
nosing the genus and describing the shape of all the species except 
O. intestinalis; brief citations are made of the work of ZELLER, ENGEL- 
MANN, and NusspauM, upon the rapid division in the spring and en- 
cystment; he mentions having, frequently himself seen, in O. rana- 
rum, conjugation preceeding the rapid multiplication in the spring 
[doubtless it was oblique division already correctly described by 
ZELLER |. 
Entz (1888) [whose paper I have been unable to obtain] is 
quoted as saying that Opalina upon a partly shaded slide will swim 
out of the lighted area into the shaded area [a result not confirmed 
by other students]. 
Biscuit (1887—1889) in his great work upon the Protozoa in 
Bronn’s Klassen und Ordnungen des Thierreichs, gives [not quite com- 
plete] literature references to that date. He describes the genus, 
giving figures of O. ranarum, O. dimidiata and O. intestinalis. He 
[mistakenly] suggests that the oblique division described by ZrLLER 
was propably conjugation. The figures of mitosis, apparently taken 
from PrirzNer, are inaccurate. He [mistakenly] says (p. 1500) that 
the nuclei lie close under the cuticle, irregulary distributed in a 
single layer. He says the nuclei are comparable to micronuclei, not 
macronuclei [They are probably comparable to both, each nucleus 
being both nutritive and generative]. 
Fasre-DomerGue (1888) mentions with approval Birscuur’s (1886) 
“first” ') description of alveolar protoplasm in Ciliata, observed in the 
ectosare [Biscuit says endosarc| of O. ranarum. 
Verworn (1889) found that Opalina [probably O. ranarum]| gave 
no reaction to stimulation by light. The center of a drop of water 
was brilliantly illuminated while the rest remained dark. There 
was no difference in the behaviour of the Opalinas in the two areas 
1) Leypie (1857) had already mentioned the “beautifully cellular structure” 
of the eetosare of Opalina. 
