18, 4 Haughwout: Human Coccidiosis 461 
tained until 12.40 o’clock, when the sporoblasts were seen 
to have elongated (Plate 2, fig. 1) and there was a distinct 
separation of the protoplasm from the membranous capsule 
that had formed externally, while the granular cell contents 
showed a tendency to clump toward the center of the cells. 
Beyond changes in the positions of the sporoblasts, nothing 
further was observed during the day; a defect in the mounting 
resulted in the loss of the cyst during the night. 
This clumping of the granules and differentiation of the 
protoplasm observed in this particular cyst is not the invariable 
appearance. More frequently, it would seem, sporoblasts retain 
their spherical form for a while in the sporocyst state, and the 
distribution of granules through the cells remains fairly uniform, 
as is seen in Plate 2, fig. 2, which was drawn from another 
specimen. Moreover, development of the sporocysts is not 
necessarily synchronous, as will be seen by another cyst (Plate 
2, fig. 3). 
The next steps in’sporozoite formation would seem to consist 
in the elongation of the sporocysts which often, although not 
invariably, become titled at an angle to the long axis of the 
odcyst (Plate 2, fig. 11) ; the gradual condensation of the proto- 
plasm into a more-compact mass; and the concentration of 
the so-called sporocystic residuum toward the center of the 
sporocysts. ; 
Unfortunately, I have been unable to find material that will 
yield information as to the further steps in sporozoite formation. © 
_ Indeed, the process. of sporogony could scarcely be worked out 
completely in the study of material obtained from a limited num- 
ber of stool examinations. The only cyst I found that seemed 
to show a definite step (Plate 2, fig. 4) had been in the ice box 
at 10° C. for forty-eight hours. It was rather difficult to focus 
down through the mass of granules and distinguish the details 
at the lower focal levels; but the protoplasm had apparently ex- 
pelled the nutritional granules, undergone concentration, and 
assumed a crescentic form preparatory to the first sporozoite 
division. That was the only cyst I have so far encountered 
that showed definite evidence of any stage between the sporocyst 
and the completely developed tetrazoic spores (Plate 2, figs. 5 to 
12; Plate 3, fig. 10). 
The cyst shown in Plate 8, fig. 6, is in all probability a cyst 
that had undergone partial sporozoite development through the 
first sporozoite division in one sporocyst, but had failed of 
further development through some untoward external condition, 
