32 
PROPHYLAXIS OF MALARIA. 
brown pigment collected in small clumps throughout the cytoplasm. 
The pigment may be very motile, especially just before exflagellation, 
and this serves to distinguish it from the female gamete , in which 
the pigment is motionless. 
The phenomenon which distinguishes the living microgametocyte 
from the forms occurring in the human life cycle is the process 
known as flagellation, during which the microgametes are finally 
extruded and liberated from the parent organism. The gametes 
that are about to undergo this change are easily recognized because 
of the violent activity of the pigment within them, and the undu- 
latorv movements of the periphery of the parasite, due to the flagella 
or microgametes moving about within the organism. If such a para¬ 
site be watched it will be observed that eventually a number of deli¬ 
cate filaments suddenly make their appearance at the periphery of 
the organism and lash about in the blood plasma. After a variable 
time one, or perhaps all, of the flagella or microgametes succeed in 
freeing themselves from the parent body and disappear among the 
red-blood corpuscles. Sometimes these free microgametes are dis¬ 
covered apparently alone in a blood specimen by the movement 
which they impart to the red corpuscles in their vicinity and have 
been mistaken for very minute filarioe. Their presence is sufficient 
to stamp the individual from whom the blood was obtained as a 
u carrier ” of malaria. 
The female gamete or macrogametocyte. —The tertian macrogame- 
tocyte when fully developed measures from 9 to 11 microns in 
diameter, is circular in shape, and almost fills the infected red cell. 
The cytoplasm is more granular than is that of the forms of the 
human life cycle, and the pigment is coarser in character and instead 
of being distributed throughout the cytoplasm is collected in a 
wreathlike manner at some distance from the periphery. The pig¬ 
ment is not motile. The arrangement of the pigment is characteristic 
and is of great value in the diagnosis of this gamete in living 
specimens. 
Stained preparations. —While it requires considerable practice to 
distinguish the gametes of the tertian plasmodium from the forms 
concerned in the human life cycle in living specimens, it is quite 
easy to make the distinction in stained preparations, and in such 
preparations even the young gametes may be differentiated from the 
“ ring-forms ” of the human cycle. The staining reactions of the 
cytoplasm and nucleus of the malaria plasmodia have already been 
described, and the only variation that occurs in the staining reactions 
of the gametes consists in the degree of color imparted by the stain 
to the various forms. The tertian gametes when stained with the 
Wright method consist of a mass of blue cytoplasm, inclosing the 
