BY DR. A. JEFFERIS TURNER, M.D. LOND., D.P.H. CAMB. 109 . 
(2) By isolation of all infected by mosquito netting. This 
is impracticable. To some extent the healthy may be 
protected by netting, but the isolation from mosquitos is 
difficult to sustain. (3) By exterminating the Anopheles 
in its larval stage (a) by drainage (b) by screening all 
domestic water, and (c) by periodical spraying of all exposed 
feeding places with some form of petroleum. In this way 
various places have already been freed from malaria, if 
not entirely at least for the greater part. No doubt the 
task before the sanitarian is immense, but malaria is no 
longer inevitable. If we continue to sufter, it will not be 
for lack of scientific knowledge, but because of the ignorance, 
indifference and indolence of mankind. 
MOSQUITOS AND YELLOW FEVER. 
As Yellow Fever is fortunately unknown in this part 
of the world, it is necessary to give you some idea of what 
the disease is. This can be best done by comparing it to 
a disease with which most of us are familiar—Dengue. 
Like that disease, it has a sudden onset with fever, shivering, 
headache, pains in back and limbs, nausea, vomiting, and 
other symptoms. This stage lasts from a few hours to 
a few days, and is followed by a remission, known as the 
stage of calm, in which the symptoms subside. In favour- 
able cases, this is succeeded by convalescence, but in others 
the temperature again rises, jaundice develops rapidly, 
and in bad cases altered blood is ejected from the stomach— 
the “black vomit’’—bleeding occurs into the skin or other 
organs, or from the kidneys, and the patient dies. Like 
Dengue, it attacks a large proportion of the population, 
but unlike that disease it is fatal in a large proportion of 
cases, from 15 to 85 per cent. The towns of the Southern 
United States have been frequently the seat of epidemics. 
In New Orleans, in 1853, there were 29,020 cases, with 
8101 deaths. In 1793, the town of Philadelphia contained 
40,144 inhabitants, of whom 4,041 died of yellow fever— 
just one-tenth. I will not harrow you with details of these 
epidemics, I mention these facts merely that you may realise 
the importance of the question, that for over a century 
puzzled the medical profession of the United States, the 
question as to how yellow fever was spread. At first it 
