36 
PROPHYLAXIS OF MALARIA. 
4. Pigment: The distribution of the pigment throughout the cyto¬ 
plasm, the pigment of the macrogametocyte being concentrated at or 
near the center. 
5. Size: The microg ametocyte s are shorter and broader than the 
macrog ametocytes. 
I do not consider it necessary to describe more minutely the mor- 
«/ */ 
phology of the estivo-autumnal gametes , as their crescentic shape is 
sufficient to distinguish them in either fresh or stained preparations 
of blood, and as their recognition is only of importance in malaria 
prophylaxis, this end will be attained bv attention to the diagnostic 
points already mentioned. For a more detailed description the reader 
is referred to any of the modern works dealing with the malarial 
fevers. 
It should be remembered that after the crescents reach the middle 
intestine of the mosquito the crescentic shape is lost; they become 
circular in outline, the male crescent flagellates, and the flagella, or 
microgametes , are liberated and fertilize the female, as in the tertian 
and quartan parasites, after which a similar cycle of development 
occurs in the mosquito. The process of flagellation is often observed 
in blood removed some time from the body, especially if a little 
moisture is present upon the microscopic slide. 
Important differential points in the diagnosis of the species of 
malaria plasmodia. —The various species of malaria plasmodia may 
be easily differentiated in both fresh blood and in stained prepara¬ 
tions if certain morphological peculiarities of the plasmodia and the 
cells infected by them be remembered. The following points I have 
found most useful in differentiating the various species: 
A. Plasmodium vivax (tertian plasmodium). 
Unstained preparations. —1. Comparatively large size of parasite 
after development of pigment. 2. Enlargement of the infected red 
blood corpuscle. 3. Active ameboid motility. 4. Fine, light-brown 
or reddish-brown pigment. 5. Number of spores or merozoites , 12 
to 24. 6. All stages of development present in the peripheral blood. 
Stained preparations. —1. Large size, after development of pig¬ 
ment. 2. Increased size of the infected erythrocyte. 3. Presence of 
Schuffner's dots (eosinophilic granules) in cytoplasm of infected 
erythrocyte. 4. Number of merozoites. 12 to 24. 5. Presence of all 
stages in the peripheral blood. 
B. Plasmodium malarice (quartan plasmodium). 
Unstained preparations. —1. Medium size, after development of 
pigment. 2. Pigment in coarse, dark-brown granules, arranged about 
periphery of organism. 3. Infected erythrocyte not enlarged at any 
stage of development. 4. Presence of all stages in peripheral blood. 
5. Number of merozoites , 6 to 12, 
