Opalina. 325 
described by EnrenseraG is no true mouth but a mere fold of the 
surface as may be seen after the body has been distended by 
adding a little dilute solution of iodine, alcohol, or acetic acid (STEN) ; 
that no nucleus was found by Sreiy; that contractile vacuoles are 
wanting; that the cilia are disposed in longitudinal lines; that the 
species is common in the intestine and bladder of frogs; that “the 
absence of a mouth affords evidence of the merely transitive nature 
of Opalinoea”, that “these simple beings are not independent but 
the mere embryonie or transitional phases of other animals”, that 
“they are probably larvae of various worms”, “consequently this 
group of beings is at best but provisional, serving only the purposes 
of definition and nomenclature”; that ,neither the intimate structure 
nor the developmental history of the Opalinoea is sufficiently well 
understood for them to be arranged in well-defined genera; that 
O. tritonis (Perry) “is very like O. ranarum and requires further 
examination”; that O. nucleus, O. entozoon and O. intestinalis ,... are 
nothing more than different phases of growth and development of 
Opalina ranarum“. Two unnamed and unrecognisable figures are 
given. 
K6LurKER (1864, p. 24) recognises the many nuclei of O. ranarum 
as true nuclei and for the first time mentions the cysts, which he 
describes as multinucleated. He regards the cysts as eggs, and 
thinks that the fact that Opalina develops from eggs confirms 
Max Scuuurze’s view that they are developmental stages of metazoa. 
QUENNERSTEDT (1865) discusses the organization of the [nfusorza, 
making but brief reference to Opalina. In his description of species 
he treats O. ranarum, giving fairly good figures. 
Stem (1867) opposes (p. 10) Lrypre’s belief that the Opalinas 
are multicellular, saying that O. intestinalis is clearly not so, and 
that the numerous clear vesicles of O. ranarum, O. dimidiata and 
0. obtrigona, which are demonstrated with acetic or chromic acid, 
are not nuclei, but are vacuoles of liquid containing granules. The 
structure of the Opalinae therefore, does not confirm belief in the 
multicellular nature of the Protozoa. The binucleated Opalinas are 
classed as numbers of his genus Anoplophrya. On p. 311 brief 
reference to the synonomy and occurrence of these forms is made. 
CuaparrpeE & LacuMann (1868, p. 373) class the Opalinae, with 
many of the other forms now placed as members of the family 
Opalinidae, as an appendage to the ciliate Infusoria. 
LaNKESTER (1870) excludes from the genus the forms now called 
Opalina, reserving this name for the species “so frequently found in 
22* 
