1888 - 89 .] Dr R. W. Felkin on Tropical Diseases. 
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winds rapidly changing the atmosphere carry away the morbific 
elements before they have time to do harm. 
Water can convey the malarial poison, but it is unknown at 
present how far it can carry it or how long the poison can remain 
unimpaired when carried either by a stream or a current. 
From what has been said, some idea may be obtained of those 
factors requisite for the production of the malarial poison. It is in 
all probability due to a micro-organism which may find entrance 
into the body by means of the air, by drinking water and possibly 
also by the consumption of food contaminated by it. It is certainly 
ponderable, as is proved by the effect of altitude, of barometrical 
pressure, and by the action which winds have in its dissemination. 
It is also miscible with water. We may sum up our definite knowledge 
of the disease by saying that it requires for its production a specific 
germ, suitable soil, a certain amount of moisture, a sufficiently high 
temperature, and a certain time for development. 
An examination of the map, bearing what has been said in view, 
will I think show how the presence of malaria in the various 
quarters in which it exists is to be accounted for by physical 
phenomena. 
II. Dengue. 
(See Plate II.) 
Synon . — Dandy Fever (West Indies) ; Third Day Fever ; Red 
Fever; Leg Fever; Breakbone Fever; Scarlatina Rheumatica 
(Aitken) ; Aburukah, or Aburuka-bar, or Father of the Knee 
(Arabia) ; Nadak-Mariata, or the Deity (Southern India) ; Tootiah 
(Bengal) ; Kidniga pepo, i.e ., Spasmodic pains (Zanzibar); Fr. and 
Ger. Dengue. 
Definition . — An infectious, eruptive fever, commencing suddenly, 
and characterised by severe pain in the head and eye-balls, swelling 
and pain in the muscles and joints, prone to shift suddenly from 
joint to joint, catarrhal symptoms, sore throat, congested con- 
junctivae, and affection of the sub-maxillary glands. The disease 
may remit, and is liable to relapse. 
Geographical Distribution . — Dengue has been known since 1780, 
in which year it attained a considerable diffusion in the tropical 
and sub-tropical parts of both eastern and western hemispheres. It 
