MALARIAL PROPHYLAXIS— SEGREGATION 
229 
of travellers of all kinds to camp in the village clearing, often to sleep in the native 
huts. 
Here, again, we find the inevitable result. Although the traveller may not 
pay much attention to their bites, the Anopheles from the huts have injected malaria 
parasites (sporozoits) into his blood, and ten days later he is ' down with fever.' 
Here, briefly, though it is a most important practical point, we must consider 
the question of flight of Anopheles. As the result of very numerous observations 
and experiments both in Africa and India, we may emphatically state that Anopheles 
do not often fly a quarter of a mile, and practically never half-a-mile. We are 
considering, it must be understood, the habitual, not the possible maximum, flight. 
Anopheles, in fact, tend to leave but for a short distance the thatched huts in which 
they spend the day, and although we give a quarter of a mile as a maximum flight, 
yet a segregation of one hundred yards from a native hut is infinitely better than 
none at all. Also, every natural obstacle tends to aid segregation, and should be 
taken advantage of, as the ridge of a hill, a belt of trees, bananas, bamboos, etc., and 
though a well-isolated dwelling, with no native families within a quarter or half-a- 
mile, should be aimed at, yet when native huts exist which it is impossible to remove, 
they should be as completely screened as possible by the planting of bananas, etc. 
To sum up these various conditions we may say that a European who 
pitches his camp or builds his permanent quarters half-a-mile, to take an extreme limit, 
from any collection of native huts, however small, will avoid infection otherwise 
almost inevitable, and if in his compound he allows only those servants absolutely 
necessary, he is in a position to escape the dangers of life in tropical Africa. 
PERSONAL PRECAUTIONS 
We cannot emphasize finally too strongly the need at present for these. We, 
ourselves, by unremitting care, completely escaped contracting malaria during over 
three years' residence in Africa and India ; in places, too, where, more frequently 
than not, the deadly conditions we have described existed. Among these precautions 
we place the proper use of a mosquito net as by far and away the greatest means of 
individual protection. 
1. Mosquito net. — The net should be square (not a bell net), should not 
have a single, even minute, hole, should hang inside the poles if these are used, 
should be tucked in under the mattress, and should not trail on the ground. A piece 
of closely woven material, fastened on all round at the level of the body is a necessary 
addition, in order to protect the limbs during sleep, from bites through the net. 
When not in use the ends of the net should be twisted up somewhat, and then 
thrown over the top. We always arranged our nets ourselves, never trusting to 
servants, and further, to be doubly certain, we always carefully searched the interior 
with a candle before going to sleep. To these minute precautions, solely, we attribute 
