Opalina. 34] 
of the body in the midst of which is an anal aperture leading from 
a short rectal tube. The position of the mouth indicates the true 
ventral surface, the animals having bilateral symmetry. [In careful 
study of living animals, and of preparations of total objects and 
sections, of O. dimidiata and other species, I have found no trace of 
any of the organs mentioned, and cannot believe them to be present.| 
KunstLer & GinestE (1906 6) describe the protoplasm of ab- 
normal O. [dimediata?| (kept too long in pure water, or from frog 
kept too long in captivity [?]) as resembling a continuous gelatinous 
substance, the appearance of a net, seen in the protoplasm of normal 
animals, being no longer discernable. 
SCHNEIDER (1906), after studying iron-haematoxylin sections of 
O. ranarum, quotes with approval (p. 48) Marer’s statement that the 
ectosarc is homogeneous [apparently referring to only what I have 
called the snbcuticular layer, since he later mentions the presence 
of large spaces filled with a thick substance, which were doubtless 
the large alveoles of the ectosarc]. He describes (p. 49, Fig. 14 a—c) 
the appearance of threads, coarser and finer, which one sees in iron- 
haematoxylin preparations, distinguishing coarser branching fibres, 
connected with the basal granules of the cilia, from more delicate 
ones forming a network not connected with the cilia. At the nodal 
points of this delicate network one sees thickenings. The coarser 
threads lie chiefly in the ectosarc, but extend also into the endo- 
sarc, the finer threads lie throughout both ectosare and endosare. 
Lying upon the latter [error| are found the disc-shaped granules 
{refractive spherules|] described by ZenLer. ScHNEDER strongly 
opposes Biscuit's conception of the cytoplasm of the Jnfusoria as 
alveolar, saying that the threads described form clearly a frame- 
work within the cytoplasm, such as is present in the ciliated cells 
of Metazoa. |Had Scunerper studied sections of Opalina, especially 
O. intestinalis or O. caudata, which had been stained with Enruicnr’s 
triacid mixture and others stained with methyl violet, he could 
hardly doubt the alveolar nature of both ectosare and endosarc. The 
threads he describes seem to me chiefly optical sections of the walls 
of the alveoles.} Scunemer describes (p. 50) and figures (his 
Fig. 14¢ and d) the appearance [described by TOnniGES, Mater and 
BrezzenBerGer. Cf. my Plate I, Fig. 2] of longitudinal markings 
between the rows of cilia, and other similar transverse markings at 
a more internal level. He says the latter have no connection with 
the cilia. [T6nnices, and, in the present paper, I also, describe the 
transverse fibrils as uniting the bases of the cilia.) SCHNEIDER 
23* 
