89 
HiEMATOZOA OF VERTEBRATES. 
"or in other words that the monozoite exists in a state of 
tension. 
In the next stage the anterior end of the monozoite (always the 
anterior end) is found to have perforated the wall of the cytocyst 
and begins to push its way out through the opening thus produced 
(figs. 30-35). 
In some cases at the moment of fixation of the blood-film on the 
slide the monozoite had extruded its body as far as the middle of 
the nucleus which appears constricted. In other instances only 
the hinder end lies still within the cytocyst and corpuscle, the rest 
of the body being free. Sometimes instead of emerging from the 
corpuscle the monozoite comes out of the cytocyst into the 
substance of the corpuscle (fig. 33). We regard this as an 
abnormal condition. 
Occasionally the cytocyst membrane is difficult to distinguish, 
and the monozoite appears to lie in the corpuscle without a sheath. 
In such cases the membrane can often be identified on close 
inspection, but sometimes no trace of it can be seen. The 
preparations here and there show some indications of an attempt 
on the part of a monozoite to re-enter the corpuscle. This may 
sometimes happen. 
Growth Forms. 
According to our observations the monozoites which emerge 
from the cytocysts are all of the same size within the limits of a 
slight variation. 
In the plasma of the blood some are much larger than others, 
especially in point of width (figs. 36-37). The staining reactions 
of all are the same, namely, pale blue cytoplasm and dense 
reddish-blue nucleus. 
In a few rare instances we have observed stages in the forma - 
fcion of the monozoite within the cytocyst. In these cases the 
condensation of protoplasm is incomplete, the pale-blue merging 
Imperceptibly into the substance of the cytocyst. Above all the 
nucleus shows unmistakable signs of formative activity in the 
definite distribution of its chromatin (fig. 29). 
Involution Forms, 
In a fewcorpuscles we have found bodies which are apparently 
monozoites undergoing degeneration. The nucleus appears to be 
fairly normal, but the cell protoplasm (cytoplasm) is reduced and 
sometimes indefinite (fig. 38). Such cases may possibly be 
due to some mischance, such as the re-entry of a monozoite into 
a corpuscle of the same host. 
8(3)04 n 
