18 
PROPHYLAXIS OF MALARIA. 
slight puncture made with a lancet or needle, and the first drop or 
two of blood allowed to flow away. A very small drop is then taken 
upon the center of a microscopic slide which has been carefully 
cleaned and a cover glass placed gently over it. If the slide is clean 
and the drop of blood small the weight of the cover glass will cause 
the blood to spread evenly and quickly beneath it; but if it does not, 
very slight pressure will suffice to spread the blood and will do no 
harm. If upon examination it is found that the blood cells are in 
clumps or rouleaux, the preparation should be discarded and one 
prepared in which the red cells are spread singly and eventy over 
the microscopic field. The preparations should be examined as soon 
as possible-; but if carefully wrapped in tissue paper, they may be 
carried in the pocket for several hours without much danger of 
changes occurring which will obscure the plasmodia; and if the 
specimens be carefully ringed with vaseline, they will keep for as 
long as 12 hours. The ear is preferable to the finger for obtaining 
blood, especially in children, as there is less pain and the patient can 
not watch the operator during the procedure. At least a half hour 
should be spent upon the examination of the specimen before a 
negative report is returned, and at least three or four preparations 
should be examined. In the vast majority of active infections, how¬ 
ever, a few moments examination will disclose the plasmodia, but 
where a search is being made for latent infections and “ carriers ” 
it is not safe to consider a case as negative unless several speci¬ 
mens are carefully examined. 
Preparation of stained specimens .—All that is necessary in the 
way of apparatus for preparing blood smears for staining are micro¬ 
scopic slides and a needle with which to make the puncture in the 
ear-lobe or finger. After cleansing the ear or finger, as described, a 
puncture is made with the needle and a small drop of blood caught 
upon the surface of a clean microscopic slide, near one end; as 
quickly as possible the end of another slide is placed in contact with 
the drop of blood, either before or behind it, and the blood alloAved 
to spread along the edge of the applied end. As soon as this occurs 
the upper or applied slide is. pushed or drawn gently along the 
surface of the slide containing the drop of blood, and when this is 
properly done a thin even smear is obtained. Several smears should 
be prepared from each individual examined. 
Method of staining .—Many methods have been devised for stain¬ 
ing the malaria plasmodia, but I have found Wright’s modification 
of the Eomanowsky stain as satisfactory as any, and it is absolutely 
reliable when the staining solution is properly prepared and used. 
Considerable time and care are necessary in the preparation of the 
stain, and this has been urged as an objection to its use, but anyone 
who will carefully follow the directions that follow will have no 
