Opalina, 993 
rectum and their study with an immersion lens necessarily takes 
much time. I am, therefore, not delaying the publication of this 
paper until all of these sections have been made and studied. If 
from this study further results of interest are obtained, they will 
be communicated later. 
In the material from the older infections one finds very many 
peculiar nuclei of huge size, much more pointed than usual and 
with peculiar spindles and chromatin (Figs. 222—227, Pl. XXV). 
It seems probable that these are copulated nuclei (syncaria). This 
is strongly suggested by such a condition as we see in Fig. 188, 
Pl. XXIV, in which we see the very pointed distal ends of the 
nuclei developed even before the two nuclei have fused at their 
apposed surfaces. I have not yet found such a spindle form in 
each nucleus in binucleated individuals, or in one nucleus while the 
other nucleus is in division according to the regular “asexual genera- 
tion” type. I have however often found uninucleated gametes in 
a late stage of nuclear division in which the forming daughter 
nuclei were both of the peculiar type just described (Figs. 226, 227, 
Pl. XXV). It is doubtful whether the spindle form of these nuclei 
indicates division. The syncaria in many species of Protozoa are 
spindle shaped when not in division.t) It is probable that such of 
my material as is carefully preserved does not include old enough 
infections to determine fully the phenomena following the copulation 
of the nuclei. 
Coun (1904) has described fundamentally different phenomena 
in the conjugation of O. intestinalis. It is evident that the animals 
seen apparently in conjugation could not have been Opalinae. The 
character of the nuclei, as well as the manner of the conjugation 
shows this. The brief unillustrated description of conjugation in 
O. ranarum, given by Licrer & Dusoscg (19044) is also fundamentally 
different and is probably erroneous. They say that two Opalinae 
“resembling those of the ordinary cysts“ come together by their 
anterior ends, lie for a long time rubbing against each other and 
turning, and then from a cyst which contains the two, each animal 
occupying half of the cyst. These phenomena are so divergent from 
those observed by other students that the description can hardly be 
accepted without confirmation. It is possible that Liarr & Duposce 
mistook the encystment of a dividing individual for conjugation, 
though with such experienced observers this seems improbable. 
1) Somewhat similar spindle-shaped nuclei of peculiar appearance are found 
in degenerating O. obtrigona. 
20* 
