Opalina. 365 
Figs. 111—115. Optical sections of other nuclei in similar conditions. Note 
that in Fig. 111 there are two chromatin-covered spheres upon the pseudo- 
spindle. 
Figs. 116 and 117. Nuclei which have almost completely degenerated, showing: 
only one or two masses of debris within the still intact nuclear membrane. 
Fig. 118. An optical section through a part of the body showing two nuclei 
and the remains of eight or nine others. In some cases merely an empty space 
marks the former position of a nucleus; in other cases one sees small spheres, the 
remains of the chromatin-covered spheres; in other cases there are left merely 
masses of debris representing the achromatic structures. 
Plate XXII. 
Opalina intestinalis. Figs. 137—139 O. caudata. 
All figures reduced one-third, to the magnification indicated. 
Fig. 119. A small individual with eight chromosomes, from a tadpole of 
Bombinator pachypus, infected 5 days. This Opalina passed unencysted through 
the alimentary canal of the tadpole. Acetic-carmine. X< 673 diameters. 
Fig. 120. A small individual with four chromosomes, from the same tadpole. 
It passed unencysted through the alimentary canal of the tadpole. The reduced 
number of chromosomes is seen in animals of this size and smaller. Acetic-carmine. 
< 673 diameters. 
Figs. 121—128. Optical sections of minute individuals about ready for en- 
cystment, from the rectum of an adult Bombinator pachypus. Figs. 121 and 122 
show respectirely an early and a late stage of the Jast division before encystment. 
Observe that the nuclei are not in mitosis. In Figs. 122 and 123 the posterior 
end of the body shows a very delicate peilicula and numerous slight lobulations. 
In each nucleus the chromatin spheres are shown, and in most of them the group 
of achromatic granules is drawn. The cytoplasmic structure is either omitted or 
conventionally drawn. The ectosare spherules are shown in Figs. 123 and 128. 
In Figs. 121, 126 and 127 probably the larger spherules belong to the ectosarc, 
the smaller to the endosare. Acetic-carmine. X< 673 diameters. 
Fig. 129. An optical section of an individual which had begun to encyst. 
Endosare spherules (shaded. more abundant in the anterior part of the body) and 
a few ectosare spherules (unshaded, in the posterior end of the body) are shown. 
The nuclear and cytoplasmic structure is not carefully drawn. Acetic-carmine. 
< 673 diameters. 
Figs. 130—132. Optical sections of cysts from the rectum of an adult Bom- 
binator pachypus. In Fig. 130 the unusually small endosare spherules are drawn. 
Fig. 131 shows one chromatin sphere in the nucleus, Fig. 132 shows three. Acetic- 
carmine. X< 673 diameters. 
Fig. 133. The nucleus of another cyst from the same preparation, showing 
only the reticulate character of the superficial chromatin in the chromatin sphere. 
Acetic-carmine. >< 1010 diameters. 
Fig. 134. An optical section of a newly formed cyst with very delicate 
wall, from the same preparation. There are three chromatin spheres in the nucleus. 
The ectosare spherules are at the outermost edge of the ectosare. Acetic-carmine. 
673 diameters. 
