286 E. A. MINCHIN. 



The cysts are covererl by a layer of flattened epithelium 

 which also forms the hollow stalky and is continuous with the 

 peritoneal epithelium covering the blood-vessels. This is best 

 seen in section (fig. 15 a). The wall of the cyst proper is 

 formed by an external very thin jelly-like layer, which cannot 

 be plainly seen in sections, and internally to this a strong 

 structureless membrane, appearing in section as a double con- 

 toured line (fig. 15). The cysts themselves are exceedingly 

 opaque, and nothing can be learnt as to their contents without 

 further preparation. They are quite spherical, and have no 

 ornamentation of any kind. 



In the sporulation I have observed three stages : 

 1. The sporoblasts (fig. 11, a, b, c). Many cysts occur filled 

 with little spherical nucleated masses of protoplasm. In the 

 living condition (11, a) they are filled with strongly refringent 

 granules, the central nucleus appearing as a faint clear space. 

 They are surrounded by a double contoured membrane. After 

 fixing and staining (fig. 11, b, c) the nucleus is distinct in 

 many of them, but they do not stain easily, perhaps on account 

 of the thick cell- wall. When visible the nucleus can be seen 

 to have irregular aggregations of darker stained substance 

 round the edge, and to be lighter towards the centre. These 

 bodies are the final results of the segmentation of the proto- 

 plasm within the cyst, or the sporoblasts. They also occur 

 singly in cysts containing spores, which is probably due to 

 arrested development. In one cyst I found, besides great 

 numbers of sporoblasts, a few nucleated masses of protoplasm 

 of various sizes containing one to three nuclei (fig. 11, d,f) 

 which were much larger than the nuclei of the sporoblasts. 

 Their structure was difficult to make out on account of the 

 opacity of the protoplasm, but in one instance a nucleus could 

 be seen to contain vacuoles (fig. 11,/), and two other nuclei 

 were found isolated and had a vacuolar structure (fig. 11, c), 

 recalling the nuclei of the adult Gregarine. The exact rela- 

 tions of these masses of protoplasm could not be made out with 

 the method employed, and it was only certain that they were 



