54 
MALARIA 
in bobbinet cages containing not more than 
20 or 25 insects to a cage. If one end of 
the cage is covered with black bobbinet the 
mosquitoes are more easily seen. Previous 
to application the mosquitoes are chilled in 
an ice box, and in the meantime a hyper¬ 
emia of the donor’s skin has been produced 
by a hot water bottle placed on that part of 
the body to which the caged mosquitoes are 
to be applied. When the cages are applied 
to the skin the chilled mosquitoes are at¬ 
tracted to the donor by the heat. The arms 
or thighs are convenient sites for applica¬ 
tion. Subsequently the fed mosquitoes are 
separated from the unfed, and the former 
are stored in a 20° C incubator. Every 
two days they are given an opportunity 
to feed on an immobilized rabbit. Those 
dying naturally are removed daily and dis¬ 
sected if their condition permits, and ex¬ 
amined for the current stages of the para¬ 
sites. If at the end of ten days none have 
died, 8 or 10 should be killed for dissection. 
After parasites have migrated to the gland 
they are stored at a lower temperature and, 
until used for inoculation purposes, are 
given an opportunity to feed on an animal 
but once a week. When required for inocu¬ 
lation they are previously starved for sev¬ 
eral days, then transferred to individual 
cages for application to the patient. The 
same technique of application is followed 
as previously described although more pa¬ 
tience is necessary. Those feeding are 
killed and their salivary glands removed 
gnd examined for the presence of sporo¬ 
zoites. 
Dissection 
Engorged wild mosquitoes should be kept 
in a cool incubator for several days prior 
to dissection, until the stomach is emptied 
from digestion. Kill not more than 2 or 3 
mosquitoes at a time with chloroform. If 
several are killed at once, place those not 
immediately required in a moist chamber. 
After identification cut off the wings and 
legs. Place the mosquito on a slide on the 
stage of a dissecting microscope with the 
abdomen pointing into a drop of saline. 
Secure the mosquito on its back or side by 
piercing the thorax with the point of a 
straight needle held in the left hand. With 
a curved needle, held in the right hand, 
nick the seventh or eighth segment above 
and below, then insert the needle point in 
the last segment and pull gently, drawing 
out the intestinal tract and appendages into 
the saline solution. Trim off the Mal¬ 
pighian tubes leaving enough to identify 
the posterior end, and cut through the fore 
and hind guts close to the stomach. Trans¬ 
fer stomach, on the needle tip, to a clean 
drop of saline—straighten it out and cover 
with a cover slip for examination in a fresh 
condition. If excessively contracted, the 
stomach may be expanded by cautiously 
warming the slide. 
In the dissection of gravid mosquitoes it 
may be difficult to remove the stomach in 
the manner described, since the ovaries 
block the opening and the tissues may 
break. In this case tear the membranous 
sides of the abdomen with the needle points 
and dissect out the stomach. 
Salivary glands. Various techniques have 
been described, some of which may be better 
adapted to certain technicians than others. 
Practice is more important than method. 
Place the remainder of the mosquito body 
in a drop of saline tinted with methylene 
Plate III—Malarial Parasites in a Thin Blood Film 
1. P. falciparum. Small trophozoites, illustrating a doubly infected cell with one marginal parasite, a 
parasite with double chromatin dot, and an uninfected cell showing basophilic stippling. 
2. P. falciparum. Microgametocyte. 
3. P. falciparum. Macrogametocyte. 
4. P. vivax. Growing ameboid trophozoite, Schiiffner’s dots clearly discernible. 
5. P. vivax. Presegmenting schizont. Another parasite in close proximity. 
6. P. vivax. Microgametocyte. Chromatin mass surrounded by vesicular area. 
7. P. vivax. . Macrogametocyte. 
8. P. malariae. Band forms, two stages of growing trophozoite. Concentration of pigment along 
periphery opposite the nucleus is apparent. 
9. P. malariae. Segmenting schizont and large trophozoite. 
