464 The Philippine Journal of Science 1921 
normal protoplasmic appearance of these cysts ‘to judge well. 
This cyst would appear to have failed of fertilization, for it was 
three days old when examined. What has happened to two of 
the other cysts (Plate 3, figs. 3 and 4) is a little hard to say, 
for they are badly degenerated. The cyst shown in fig. 3 has 
apparently suffered from osmotic changes, and the protoplasm 
presents a picture frequently seen in dying protozoa. The cyst 
shown in fig. 11 probably failed of fertilization. Its appearance 
recalled, somewhat, the appearance of the contents of an unfer- 
tilized Ascaris ovum. Five of the other cysts (Plate 3, figs. 5 
to 9) clearly owed their destruction to causes other than failure 
to secure fertilization, for they had progressed considerably 
toward complete development. Indeed, it is not unlikely that 
the cyst shown in fig. 7 actually attained full development and 
went to pieces later. The cyst shown in fig. 5 had been in 
the ice box for forty-eight hours and had then been sealed 
in 10 per cent potassium bichromate solution for twenty- 
four hours. The cyst in fig. 6 had received similar treatment, 
except that it had been sealed in physiological salt solution. The 
cyst in fig. 7 had been in the ice box for one week and had then 
been allowed to develop overnight in the laboratory. The prep- 
aration in which it was found contained numerous fully de- 
veloped and perfectly healthy cysts as well as a few others that 
had degenerated. Figs. 8 and 9 were also ice-box specimens 
that for some reason had gone wrong after sporoblast and spo- 
rocyst formation, respectively. The cyst in fig. 9 might still 
have been capable of further development, notwithstanding the 
extrusion of the endoplasmic granules. The occurrence of the 
clump of granules lying at one side of the center of the cyst 
measuring about 3.6 » in diameter, I am inclined to regard as for- 
tuitous and not to be interpreted as an odcystic residuum. 
The cyst shown in Plate 3, fig. 2, was one of the largest I 
encountered in the study. Unfortunately it was. lost before I 
could measure it. It looked startingly like a developing cyst of 
Eimeria. I had managed to draw the outlines under the camera 
lucida, when I was called to the telephone. When I returned, 
evaporation had swept it away and I was unable to find it again. 
In only one instance did I find a sporocyst that had become 
separated from its odcyst (Plate 3, fig. 12). Dobell quotes 
Wenyon and O’Connor as reporting the occasional occurrence of 
odcysts of Isospora hominis containing a single sporocyst with 
eight sporozoites. I encountered no such forms. Dobell has 
seen them occasionally in Isospora bigemina. 
