348 
Pleistoplwra girjantea, Thelohan 
and contain a relatively small number of spores. Between the cysts 
young individuals may be seen, even at a low magnification (Zeiss. Obj. 
3, ocul. 2); they ai’e free (PI. XVIII, fig. 1 a) or surrounded by a thick 
capsule of connective tissue (PI. XVIII, fig. o a). 
The following observations were made with the aid of a high power 
of the microscope (Zeiss. Apochrom. oil immersion 2 mm., oculars 4 or 18). 
{a) Trophozoites. The youngest developmental stages found are 
round or oval cells with one or more nuclei, 6'3-ll'2 /u. long and 4'6-9'8 /u, 
broad (Diagram I; PI. XVII, fig. 2). The protoplasm has an alveolar 
structure; the nuclei are very chromatophil and consequently they 
are deeply stained, which often checks the study of the internal 
structure. The nuclei are surrounded by a clear space. The proto¬ 
plasm is enclosed within a thin membrane; this membrane is very 
distinct in individuals where the protoplasm shows signs of shrinkage 
(Diagram II, Fig. 1). 
Diagram II. (Oil immersion 2 mm. ocul. 18.) Fig. I. First stage of nuclear division. 
Fig. 2. Division of the karyosome. Fig. 3. Constriction of the elongated nucleus. 
Figs. 4, 5. Final stages of nuclear division. 
The trophozoites contain one or more nuclei, and it is to be supposed 
that the mononucleate individuals are the youngest, considering that 
they are the smallest. Diagram I h suggests that the multinucleate 
individuals multiply by schizogony. 
The structure of the nuclei of the trophozoites is a simple one 
(Diagram II), some chromatic granules are supported by an achromatic 
substratum. Sometimes a central chromatic granule is present which 
perhaps must be regarded as a karyosome. The nucleus which is about 
