OBSERVATIONS UPON MALARIA: LATENT INFECTION 
IN NATIVES OF THE PHILIPPINE ISLANDS— 
INTRACORPUSCULAR CONJUGATION.’ 
By CHARLES F. CRala. 
(From the Laboratory of the United States Army Hospital, Camp Stotsen- 
berg, P. I.) 
INTRODUCTION. 
In this contribution it is my purpose to give in brief the results of some 
observations obtained upon malarial infections while I was on duty at 
the United States Army post at Camp Stotsenberg, Pampanga, Luzon, 
Peel: 
The locality mentioned is one of the most favorable in the Philippines 
for the study of malaria, as cases of the disease are numerous in which 
all varieties of the plasmodium may be observed. The post is situated 
on the western border of the great Pampangan plain, near the Zambales 
Mountains, the station proper being placed in the foothills and at a con- 
siderable elevation above the plain. The soil is volcanic in nature, and 
even after the heaviest rains in a few hours becomes perfectly dry. 
There is no stagnant water within a mile, and therefore there are 
no breeding places of Anopheles. In order to reach the post these 
insects must travel at least one mile, and as they are at all times 
numerous it will be seen that in this instance the prevalent idea that they 
fly but a short distance is disproved. There is a considerable area of 
jungle country surrounding the station, some of which is situated within 
a radius of a few hundred yards, but I have failed, after the most careful 
exploration of these jungles, to find any breeding places of the Anopheles 
nearer to the post than one mile. It was invariably found that when 
the grass about Stotsenberg was allowed to grow to any great length the 
mosquitoes to a large extent increased, this being accompanied by a 
coincident rise in the number of cases of malaria; on the other hand, 
when it was cut, both mosquitoes and malaria diminished very appreciably. 
*Read March 1, 1906, at the third annual meeting of the Philippine Islands 
Medical Association by Charles F. Craig, M. D., First Lieutenant, Assistant 
Surgeon, U. S. Army, member of U. S. Army Board for the Study of Tropical 
Diseases in the Philippine Islands. 
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