Opalina. 371 
Large reticulate masses of chromatin and some smaller fragments are seen extruded 
from the nucleus and lying in the cytoplasm. Apparently the full number of 
chromosomes (8) were in these nuclei. Vacuoles around some of these masses are 
indicated by dotted contours. From a 6 day infection. Coros. subl.-acetie acid, 
Devarietp’s haematoxylin. Restaining with iron haematoxylin gave the same 
results. 673 diameters. 
Fig. 240. The anterior end of another individual from the same preparations, 
showing a reticulate mass of chromatin slightly displaced, probably by the micro- 
tome knife, from its position in the nucleus. >< 673 diameters. 
Fig. 241. A combination of three drawings from sections of an individual 
which had passed wnencysted through the alimentary canal and had been six 
days in the rectum of a tadpole of Bombinator pachypus. Vacuoles, probably of 
the excretory system, are shown in dotted outline. Six masses of chromatin are 
seen lying in the cytoplasm. One of these is in the form of a reticulate layer 
partly surrounding a central refractive sphere (cf. the figures on Plate XXI). The 
nuclei contained the reduced number of chromosomos (4). Coros. subl.-acetic acid, 
Dervarievp’s haematoxylin. XX 673 diameters. 
Figs. 242—244. Successive sections from a small individual from a tadpole 
of Bombinator pachypus, infected 6 days. Extruded masses of chromatin are seen 
in the cytoplasm. The animal may or may not have come from a cyst so for as 
its size would indicate. It seems probable, however, that animals with this type 
of chromidia passed unencysted through the alimentary canal. Four chromosomes 
are in each nucleus. Coros. subl.-acetic acid, DrLarienp’s haematoxylin. X 673 
diameters. 
Figs. 245—247. The three central sections from a series of five through an 
individual from a tadpole of Bombinator pachypus, infected 6 days. Extruded masses 
of chromatin are seen in the cytoplasm near each of the two nuclei. The other 
two sections showed no such chromidia. Coros. subl.-acetic acid, DErLarre.p’s 
haematoxylin. > 673 diameters. 
Figs. 248—262. Opalina caudata. 
Figs. 248—250. Individuals which passed unencysted through the alimentary 
eanal into the rectum of a tadpole of Bombinator pachypus; 118 hours infection. 
Excretory vacuoles are seen in each. In Fig. 248 the boundary between ectosare 
and endosare is indicated by a dotted line. In this figure there are shown twelve 
chromatin masses (chromosomes) in each nucleus which must be ready to enter 
upon mitosis. The other animals show the reduced number of chromosomes (8). 
Acetic-carmine. > 673 diameters. 
Fig. 251. A section through a small individual from the rectum of an adult 
Bombinator pachypus which contained mauy infection cysts. In each nucleus are 
two chromatin spheres whose presence at this early stage is unusual. Coros. subl.- 
acetic acid, DeLarieLp’s haematoxylin. >< 673 diameters. 
Figs. 252—256. Infection cysts from aquaria in which Bombinator pachypus 
was kept (Fig. 254 shows a cyst from the rectum of one of these adult Bombinator). 
Fig. 252 shows one chromatin sphere in the nucleus; Fig. 253 shows two chromatin 
spheres extruded into the cytoplasm and none in the nucleus; Fig. 254 shows a 
binucleated cyst with one chromatin sphere in one nucleus aud none in the other; 
Fig. 255 shows a binucleated animal which encysted while in division; in Fig. 256 
two animals are shown inside one cyst (one cannot be certain that they are entirely 
