160 



TROCEEDINGS OF THE ACADEMY OP 



[Feb., 



Fig. 3. 



earlier stages, and the detailed account will be reserved for my final 

 communication. I shall here merely consider the latest stages in each 

 case. 



Fig. 2 shows an acidophil cell still attached to the epithelium. 

 Within it are several clear areas. Each of these is occupied by a 

 quantity of chromatin. In several cases the manner in which this 

 chromatin is arranged is strongly indicative of mitotic division. In 

 fig. 3 is shown what may be called a cyst of the round bodies. The 



original trophozoite con- 

 sists of a shell, divided 

 into irregularly shaped 

 compartments. Each 

 compartment contains a 

 completed round body. 

 The round body is nor- 

 mally spherical ; occasion- 

 ally ellipsoidal. It usu- 

 ally consists of a solid 

 mass of strongly acidophil 

 cytoplasm containing an irregular nucleus. That the element shown 

 in fig. 3 is derived from that of fig. 2 is indicated by the striking resem- 

 blance between the nuclei, and by their size. In the stage of fig. 2 the 

 nuclei are in division, and are thus, as is usual, lying within clear 

 regions. To obtain the conditions shown in fig. 3 it is only necessary 

 to conceive the collection of the cytoplasm around the nuclei, with the 

 consequent disappearance of the vacuoles. 



A little later, by the complete disintegration of the cyst, the round 

 bodies come to lie free in the lumina of the tubules. They are minute 

 elements, ranging in diameter from H-2 microns. There is probably a 

 very delicate ectosarc or membrane, since at times the cytoplasm Is 

 wanting, the chromatin lying within an otherwise empty shell. The 

 ultimate destiny of these bodies has not yet been discovered. 



The formation of the spores follows much the same general lines, but 

 differs considerably in detail. The nuclei, after passing through the 

 stage of individual chromosomes, concentrate into rings, ovals, or the 

 so-called dumbbell shape (figs. 4 and 5). Frequently they may be- 

 come wholly solid masses of chromatin, but more usually they show a 

 central cavity, or, in the case of those having the dumbbell shape, two 

 such cavities. Around this cliromatin mass there is nearly always a 

 clear space, while the bulk of the spore consists of a thick shell of acido- 

 phil cytoplasm (fig. 5). Occasionally the clear space encroaches upon 



