PROPHYLAXIS OF MALARIA. 39 
focussed upon they appear as alternately light and dark areas upon 
the surface of the red corpuscle. 
Among other bodies that have been mistaken, in my experience, 
for malaria plasmodia, and shown to me, may be mentioned yeast 
cells, bacteria of various kinds, extraneous matter, and degenerating 
red blood corpuscles possessing slender cytoplasmic processes. The 
latter have been mistaken for flagellating plasmodia, but the greenish 
color and lack of pigment should prevent such a mistake. 
In specimens of blood stained by Wright's method the following 
have been mistaken for malarial plasmodia: 
Blood plates .—There is no object so frequently mistaken for mala¬ 
ria plasmodia in stained preparations of blood as is the blood 
platelet, especially when it lies upon a corpuscle, but such an 
error is impossible if one is familiar with the morphology of the 
platelet. The malaria plasmodia of a similar size may always be 
differentiated from the platelets by their blue-stained cytoplasm and 
the solid, compact mass or masses of chromatin which stain a ruby 
red color. The chromatin of the blood platelet stains a darker 
color and is distributed throughout the platelet in the form of fine 
granules or irregular granular masses. If one remembers that any 
malaria plasmodium the size of a blood platelet consists only of a 
mass of blue-stained cytoplasm containing a solid spherical dot, or 
at most two dots, of chromatin, it will be impossible to confuse it 
with a blood platelet, which has a practically unstained cytoplasm 
and in which the chromatin is granular and collected in a mass or 
masses in the cytoplasm. Not frequently blood platelets may be 
collected in crescentic shaped clumps and these have been mistaken 
for crescents, but no one in the least familiar with the plasmodia 
could make such a mistake. 
Flaws in the microscopic slide, in which some of the stain has 
settled, have caused confusion, especially if overlaid by a red-blood 
corpuscle, but focussing will show that they are on a different level 
from the corpuscle, and a study of the staining reaction will imme¬ 
diately demonstrate their nature. 
Vacuoles in the red cell, which sometimes retain a little of the 
stain, may slightly resemble some of the stages of development of 
the plasmodia, but may be easily distinguished from the plasmodia 
by the absence of the blue-stained cytoplasm and red chromatin 
always present at every stage in the development of the malaria 
parasites. 
Among other objects which have been confused with the plasmodia 
in stained smears may be mentioned degenerating erythrocytes and 
leucocytes, yeast cells, and other microorganisms, nucleated erythro¬ 
cytes, basophilia of the erythrocyte, and extraneous bodies of various 
nature. It is perfectly obvious that a knowledge of the appearance 
