PROPHYLAXIS OF MALARIA. 
75 
Method of screening .—It is a perfectly obvious fact to anyone who 
inspects screened buildings, either in civil or military life, that much 
of the screening is so constructed as to defeat, in a measure, the pur¬ 
pose aimed at, i. e., the exclusion of mosquitoes. The use of adjust¬ 
able or folding screens; the fastening of the screen within the win¬ 
dow, necessitating its being raised every time the window is opened; 
and the use of the single-screened door for quarters and barracks, in¬ 
stead of having double-screened doors with a screened vestibule, are 
all instances commonly observed of imperfect screening. In bar¬ 
racks that Avere caiefullv screened I haA r e observed unscreened venti- 
lators along the ridgepole, which explained fully the presence of 
numerous mosquitoes within them, an occurrence which had fur¬ 
nished a strong argument against screening in the prophylaxis of 
malaria to certain individuals avIio Avere adA T erse to this method. Not 
infrequently, Avhile the first and second stories of quarters are care¬ 
fully screened, the attic windows will be found unscreened, and 
mosquitoes thus gain entrance to the quarters. All of these mistakes 
can be easily avoided and are most important in their effect upon the 
success of screening against mosquitoes. 
The arrangement of screens must vary, of course, Avith the archi¬ 
tecture of the building to be screened, but all window screens should 
be placed outside window sashes and fitted as closely as possible to 
the sash, as otherwise mosquitoes may easily get in between the screen 
and sash, especially when the window is partly open. In fact, to 
insure perfect protection the entire window should be coA^ered exter¬ 
nally by one screen. In this way either the lower or upper sash may 
be raised or lowered without danger of admitting mosquitoes. 
Where wire screening is impossible doors and windows may be pro¬ 
tected by cheese-cloth screens, which, Avhile not very durable, are sat¬ 
isfactory if carefully watched for the appearance of holes and 
promptly replaced. All entrances to quarters and barracks where 
screening is necessary should be protected by a screened vestibule 
containing tAvo doors instead of a single screened door opening di¬ 
rectly into the building, which is the usual arrangement. While this 
method of screening may be practically sufficient Avhere mosquitoes 
are not very numerous and malaria is rare, it is necessary to have the 
double-door entrance in regions where malaria prevails to anv extent, 
especially in barracks, where the doors are opened so frequently. 
All screened doors should open outward. 
Extreme care should be taken that all ventilators be screened, and 
that screens be frequently inspected and repaired promptly when 
necessary. 
Mosquito nets or bars .—When it is impossible to thoroughly screen 
barracks and quarters, and for troops in the field, the mosquito net 
or mosquito bar, as it is often called, furnishes a most valuable means 
