53 
have at last solved the problem of malaria, and of the relation of 
quinine to it. Any one who is a trained observer and who wi 
take ordinary care can now perform the following experiment : 
He can allow a mosquito to feed upon a person’ who exhibits 
the malarial disease and in whose red blood corpuscle the 
malarial animal has been found by microscopical examination. 
He can then permit this insect to feed upon another person who 
has presented no such symptoms and whose blood has been 
found uncontaminated. Asa result of this, and of no other proc- 
ess, the second individual can be brought into the same condi- 
tion as the first. The cinchona products can then be adminis- 
tered to either, resulting in the removal of the disease and its 
cause, while both persist in the other individual. The blood of 
the latter can now be drawn and tested with the cinchona prod- 
ucts, while under microscopical observation, and the fatal ef- 
fects of the latter upon the malarial animal seen to result, thus 
completing the chain of evidence to prove that this drug ts 
a true specific for this disease. There is, of course, much still 
to be learned about the conditions and methods for producing 
the best results, but the malarial dragon is practically slain. The 
little fear that the explorer or the soldier now feels for it results 
from his lack of power to control the circumstances, rather than 
from any consciousness of a want of means at command. 
Let us now supplement this glance at the history of the science 
of our subject by a brief review of the practical development of 
our present ready means for utilizing such knowledge. 
In 1638 the first undoubted cures by cinchona bark were made 
known to scientific medicine, such as it then was. One hundred 
years later the plant producing it became known to botanists, 
and unsuccessful attempts were made to bring it alive to Europe. 
During the next century the use of the bark increased to a phe- 
nomenal extent. The original districts were exhausted and new 
ones levied upon, new and superior species being discovered in 
the meantime, and their stores, in turn, alarmingly depleted. All 
of the 30 or 40 species of the genus were sought out and experi- 
mented with, but most of wae were found either wholly or 
largely wanting in active ituents. Every related plant which 
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