43 
In the first experiment the five rats in Avhich free vermicules were 
obseiwed twenty-four hours after feeding infected mites were those 
in which encysted parasites were first observed. It is probable that 
a more prolonged search for parasites in the blood of the remaining 
three rats would have resulted in the finding of a few at that time. 
An attempt was made to infect four rats by feeding them livers 
from infected rats in which cysts (containing merozoites) were nu- 
merous. The result was negative. No free vermicules were detected 
in the blood during the first twenty-four hours, nor did an}^ encysted 
parasites appear later. 
Defib rinated heart’s blood from an infected animal was injected 
into the peritoneum of two healthy rats, 1 c. c. to each rat. Blood 
smears previously made from the infected rats showed only encysted 
parasites. Result negative. 
In a later experiment defibrinated blood in which there were a few 
free vermicules was employed. The results were also negative. 
Small pieces of liver containing ripe cysts were gentl}" rubbed up in 
a mortar with salt solution. The liquid, strained through sterilized 
gauze, was injected into the peritoneum of two rats. Result negative. 
Several mites containing ripe sporocysts were gently crushed and 
rubbed in a mortar containing 0.3 per cent salt solution. The liquid, 
when strained and examined with the microscope, was found to con- 
tain many free sporozoites. A portion of the fluid was injected into 
the peritoneal cavity of two rats. Result negative. 
Action of citrate solutions upon encysted parasites. — Defi- 
brinated blood from an infected rat was added in varying amounts 
to small test tubes containing 1 c. c. of 1 per cent solution of sodium 
citrate in normal salt solution. Two tubes were set aside at room 
temperature (about 30° C.) ; two tubes were placed in the incubator 
at 37° C. for twenty-four hours. The same method of procedure was 
also followed, using normal salt solution instead of soidum citrate 
solution. Results: In salt solution kept for three days at 30° C. a 
few sluggishly motile vermicules were found. In other solutions no 
change took place in the encysted parasites. 
A series of sections were made from the middle and lower part of 
the small intestine of a fasting rat, fed twelve hours before, on a large 
number of crushed mites heavily infected with ripe sporocysts, inclosed 
in moist bread. Numerous vermicules were seen between the epithe- 
lial cells and in the capillaries and lymph spaces in the villi. 
CLASSIFICATION. 
Some zoologists have favored a classification of the gregarine-like 
blood parasites as a subdivision of the gregarines, wliile others have 
placed them in a subdivision of the Hsemosporidia, making blood 
parasitism the principal feature upon which to base the classification. 
