188 MOSQUITOES OF NORTH AMERICA 
ing Man and Nature With a Few Practical Suggestions on Other Subjects,” 
Dr. Samuel W. Francis, in 1874, made the following statement, which, in the 
light of recent developments, is a very curious instance of a conclusion dia- 
metrically opposed to the right one having been drawn from practically the same 
premises : 
“Tt is my firm conviction that the mosquito was created for the purpose of 
driving man from malarial districts; for I do not believe that in nature any 
region where a chill and fever prevail can be free from this little animal. Now 
if man will not go, after warning is given in humming accents, then the mos- 
quito injects hypodermically a little liquid which answers two purposes—first 
to render the blood thin enough to be drawn up through its tube, and secondly 
in order to inject that which possesses the principles of Quinine! This idea I 
published in a work entitled ‘ Life and Death, p. 210, March, 1871; a few lines 
will suffice. ‘The time will come when it will be publicly acknowledged that the 
little fluid they (mosquitoes) inject into your blood contains certain specific 
properties for different diseases. To prove that I am right, let any skillful 
chemist test the powerful drop contained in a mosquito’s sack, and he will find 
many of the properties of Quinine.’ ” 
A curious old account of the value of measures undertaken with the idea of 
preventing malaria, and which at the same time were incidentally antimosquito 
measures (although cause and effect were not in the least recognized), is given 
in the 15th Annual Report of the American Society for Colonizing the Free 
People of Color of the United States, Washington, 1832, p. 51. 
Joseph Reynolds, of Bristol, writing to Elliot Cresson, in the United States, 
gives an account of the measures adopted to preserve the health of the crew of 
the ship Cambridge during the period of about ninety days when she lay in the 
river above Sierra Leone. None of the crew were suffered under any con- 
sideration to be out of the ship at sunset or after. A sail was stretched on the 
windward side of the vessel and an awning was also provided which extended 
over the poop and the whole of the main-deck “ to defend the crew from the night 
air.” “The night watch was encouraged to smoke tobacco.” Incidentally, the 
hull of the vessel was kept pure by the constant use of chloride of lime. The crew 
were given a tonic treatment of strong coffee and French brandy. “ The result 
was, that the ships on each side of the Cambridge, lost the greater part of their 
crews: not one man of the Cambridge was seriously unwell, during the whole 
time they lay in the River, and it was remarked that the ship was so clear of mus- 
quitoes, that the Captain threw aside the curtains which he had provided for his 
defence against them.” Mr. Reynolds remarks that the instructions given to the 
commander were derived from reading Dr. Macculloch’s “ Essay on Malaria,” a 
work which advocated protection against the exhalations of malarial localities. 
MALARIA. 
THE MALARIAL ORGANISMS. 
The disease known as malaria is caused by parasites in the blood which feed 
upon the red blood-cells. They are unicellular animals, belonging to the Spo- 
rozoa. They have been classified in the sub-order Hemosporidia and genus 
