Opalina. 373 
some of the endosare spherules present; in the cytoplasm only the larger granules 
are carefully drawn; the living animal was treated directly with Enruicn’s acid 
haematoxylin. Figs. 278—280 are acetic-carmine preparations; Fig. 279 shows 
apparently a chromatin sphere being extruted from the anterior nucleus. Fig. 281, 
Enruicn’s acid haematoxylin. All figures X 673 diameters. 
Figs. 282—284. Spheroidal individuals, not true cysts, from a tadpole of 
Rana esculenta, infected 24 hours. From these apparently pseudocysts some of 
the endosare spherules are being extruded. My notes on these drawings, as also 
my memory of them, are insufficient to explain the conditions shown. Acetic- 
carmine. X< 673 diameters. 
Figs. 285—288. Infection cysts from tadpoles of Bufo vulgaris, naturally in- 
fected. The size of the cysts, their multinucleated condition, and the presence of 
free-swimming minute Opalinae dimidiatae in the same recta, show these to be 
eysts of O. dimidiata. Fig. 285, from a living cyst; the other figures from 
acetic-carmine preparations. > 673 diameters. 
Figs. 289-291. Peculiarly shrunken individuals which passed unencysted 
through the alimentary canal and were lying in the rectum of a tadpole of Rana 
esculenta, infected 24 hours. Endosare spherules (shaded) and ectosare spherules 
(unshaded) are shown. Acetic-carmine. >< 673 diameters. 
Fig. 292. An individual from a large tadpole of Rana esculenta, infected 
24 hours. Acetic-carmine. X< 673 diameters. 
Fig. 293. A living gamete parent-cell from a tadpole of Bufo vulgaris, in- 
fected 6 hours. The endosare spherules are shown. X< 673 diameters. 
Fig. 294. A living gamete parent-cell in division; from a tadpole of Bufo 
vulgaris, infected 36 hours. The endosare spherules are shown. The granules 
shown as black were highly refractive. The condition of the nuclei is of interest. 
X< 673 diameters. 
Figs. 295—298. Macrogametes from a tadpole of Rana esculenta. X 673 
diameters. 
Plate XXVIII. 
Opalina dimidiata and Opalina ranarum. 
All figures are reduced one-third, to the magnification indicated. 
Figs. 299—324. Opalina dimidiata. 
Figs. 299—302. Gamete parent-cells from tadpoles of Rana esculenta, infected 
respectively 32 hours, time?, 97'/, hours, 32 hours. Fig. 302 shows the endosare 
spherules and also the extrusion of chromatin spheres from each nucleus. Acetic- 
carmine. X< 673 diameters. 
Fig. 303. An individual from a tadpole (of a species not noted) infected 
8 days. The structures in the elongated nuclei were not clearly seen. It is 
doubtful whether the animal was a gamete parent-cell with both nuclei in mitosis, 
or a zygote with its syncarion already divided into two. Acetic-carmine. > 673 
diameters. 
Fig. 304. An individual from a tadpole of Rana esculenta, infected 80'/, hours. 
Its nucleus was in mitosis. The nature of the bodies at the two ends of the 
spindle was not clear; they were probably chromatin spheres similar to those 
shown extruded from the larger nucleus in Fig. 309. The animal was probably a 
microgamete mother cell. Acetic-carmine. >< 673 diameters. 
25* 
