BY DR. A. JEFFERIS TURNER, M.D. LOND., D.P.H. CAMB. 103 
century it was discovered that the attacks were preventable 
by the administration of large doses of quinine, and that 
the disease could be in most cases cured by the use of this 
drug. This discovery was valuable, not only for its thera- 
peutic effect, but in differentiating malarial from other 
fevers, which were not influenced in the same way by 
quinine. But it threw no light on the causation of malaria, 
as to which the only thing really known was that it was 
a place disease. As to what peculiar feature of the locality 
was responsible there were various theories. One ascribed 
it to something in the drinking water, and this seemed to 
be supported by the fact that many fever districts were 
marshy, and that some had been freed from fever by drain- 
age. But the most prevalent opinion was that malaria— 
as its name unplied—was propagated through the atmos- 
phere, and that the air was contaminated by exhalations 
from the soil of certain districts. But these exhalations were 
mere suppositions, and the various theories were gropings 
in the dark without a real clue. 
The first ray of light came in 1880, from M. Laveran, 
a French physician working in Algiers. Laveran discovered 
peculiar bodies inside the red-blood corpuscles of patients 
suffering from malarial fevers, and recognised them to be 
the parasites that caused the disease. This discovery was 
at first received with considerable scepticism. The parasites 
were inconspicious and hard to find. Though many diseases 
were known to be due to various bacteria, these parasites 
were protozoa, belonging to the animal kingdom, very 
different to bacteria, and incapable of cultivation outside 
the human body. Nevertheless, by the labours of many 
observers, the life-history of the parasites inside the human 
body was thoroughly worked out, and their causal relation- 
ship to the disease sufficiently established. The earliest 
stage of the parasite is a minute colourless protoplasmic 
speck inside the corpuscle. It shows active amoeboid 
movements, and gradually increases in size at the expense 
of the corpuscle, at the same time developing blackish specks 
of pigment in its interior. After reaching full size it begins 
to show signs of segmentation, and assumes the rosette 
form. Finally the rosette separates into a number of 
minute spherules or spores, the corpuscle breaks down, 
