38 
PROPHYLAXIS OF MALARIA. 
In fresh specimens of blood the following may be mistaken for 
malaria plasmodia: 
Vacuoles. —There is no object more deceiving in fresh blood pre¬ 
parations than a small vacuole within the red corpuscle, especially 
if the border of the vacuole alter in shape, when the resemblance to 
the hyalin disk forms of the various plasmodia is really very strik¬ 
ing. The greater refraction of the vacuole and the fact that it grows 
larger and smaller in focussing up and down upon it should dis¬ 
tinguish it from any stage in the growth of the malaria plasmodia. 
Retraction of the hemoglobin from the edge of the red corpuscle 
mav sometimes cause the area devoid of hemoglobin to resemble a 
hyalin plasmodium, but it may be distinguished by the lack of ame¬ 
boid motion and the sharp edge of the hemoglobin layer. 
“ Eye-spots ,” or areas devoid of hemoglobin, occurring within the 
red corpuscles are sometimes observed in normal blood, and fre¬ 
quently in typhoid fever, tuberculosis, pneumonia, and other acute 
infectious diseases. They are apparently due to retraction of the 
hemoglobin layer of the corpuscle, and may be round, oval, spindle- 
shaped, or ring-shaped, and situated at any portion of the corpuscle. 
Many of them are oval and spindle-shaped and contain a dark area 
at the center resembling pigment. These “ eye-spots" have been 
very often mistaken for malaria plasmodia and have been described 
by several observers as new blood parasites of man. The absence of 
distinct ameboid motion and the greater degree of refraction should 
serve to distinguish them from malaria plasmodia. 
Blood platelets. —A blood platelet, if lying upon a red corpuscle, 
resembles slightly the hyalin disk form of malaria plasmodia, but 
upon focussing there will be observed a difference in the level of 
the two bodies, while the platelet has no ameboid motility and is 
less opaque than the plasmodia. 
Granules derived from broken down leucocytes, which possess 
active Brownian movements, may be confused with the smallest 
forms of plasmodia if they become attached to, or lie over, the red 
blood corpuscles. Their smaller size and different structure should 
render such a mistake impossible. 
The normal lighter colored center of the red corpuscle, which is 
often hyalin in appearance in diseases accompanied by anemia, has 
often been confused with the hyalin malaria plasmodia, and I have 
several times been shown cells of this character and told that they 
contained plasmodia. Such a mistake is due to inexcusable igno¬ 
rance of the morphology of the red blood corpuscle. 
Cremations of the red corpuscle may cause some trouble to the 
beginner if they be looked down upon directly, as they then appear 
as round, hyalin bodies lying upon the red cell, and are sometimes 
slightly motile. However, there is no ringlike outline, and when 
