466 T/ie Philippine Journal of Science 1921 
31.5° C.), several cysts containing fully developed sporozoites 
were found (Plate 2, fig. 8). 
Examination of the ice-box material every day until April 
3 yielded no cysts beyond the sporocyst stage, while many in 
the late zygote and sporoblast stages were found each day. 
Each specimen was left on the table overnight and, each morn- 
ing after, fully developed cysts were found. On the morning 
of April 3, just two weeks after the experiment was started, 
fully developed cysts (containing sporozoites) were found in 
the faeces immediately after it was removed from the ice box. 
In other words, the lowered temperature, as was to be ex- 
pected, retarded the development of the cysts considerably, but 
they “picked up” rapidly on being carried into a warmer 
atmosphere and, after the third day, were capable of completing 
their development overnight in the higher temperature. The 
cold also undoubtedly favors the cysts in that it retards the 
fermentative changes in the faeces that are inimical to the cysts. 
This would seem to indicate that the temperature in the fall and 
spring months, and possibly into the early and late winter in 
temperate climates, will tend to favor the dissemination of the 
infection. It is not by any means certain that the meteorology 
of the Tropics will afford favorable conditions for the spread of 
coccidial infections. 
EFFECTS ‘OF TROPICAL SUN ON THE CYSTS 
The resistance of coccidial cysts to dessication and the action 
of chemicals is well known, but it occurred to me that it would 
be interesting to try the effects of the tropical sun on them. For 
that purpose the following rather crude (experiment was under- 
taken : 
The material used was part of the stool passed on March 16, 
which had been in the ice box forty-eight hours. At the 
time the experiment was started, none of the cysts had passed 
beyond the sporoblast stage. A quantity of faeces was emulsified 
in physiological salt solution and spread out in a very 
thin layer ,on the middle of each of a number of slides. The 
area covered was square and about equal to the area of an 
ordinary square cover slip. The slides were quickly examined 
under the microscope to make certain that they contained 
cysts and were then placed at the window in the direct rays of 
the forenoon sun, which is very hot in Manila at this time of 
the year. The slides were allowed to remain there for about 
two hours, at the end of which time they were distinctly hot, 
