THE AUSTRALIAN NATURALIST. AL 
About 1883, Dr. Manson showed that certain species of 
female mosquitoes were the intermediate host of the blood 
parasite (Filaria), which, entering the human blood, mul- 
tiplies and produces malarial fever. This Filaria is a ‘‘mi- 
croscopic animalcule, eel-shaped and enclosed in a loose sac 
in which it wriggles about in the blood most actively.’’ The 
larval form had been discovered, as far back as 1863 in the 
blood of natives in India by Demarquay, and by Lewis in 
1872. 
Later on by the examination of the blood of thousands of 
natives of China and Amoy Dr. (now Sir Patrick) Manson, 
found the actual parasite that was the cause of malarial fever, 
and the labours of Major Ross in India, explained the manner 
in which this blood parasite was introduced into the blood of 
man by the mosquito. 
Briefly stated, certain genera of mosquitoes are infested 
with this blood parasite which the mosquito sucks up when 
biting a person infected with fever. These filaria develop 
in the body of the mosquito, then make their way down into 
the salivary glands from whence they flow into the human 
blood with the fluid injected by the proboscis of the biting 
mosquito. 
When in the human blood these parasites multiply with 
such wonderful rapidity that within from four to ten days a 
man will show the first signs of malarial fever. So small are 
some of these protozoa that the one causing yellow fever has 
not yet been seen with the highest microscopic power. 
These discoveries have caused an immense amount of ‘work 
to be devoted to the collection, study and classification of 
mosquitoes all over the world. Theobald has catalogued all 
the known species in a monograph of the ‘‘Culicidae’’ com- 
prising five large volumes, pubiished by the trustees of the 
British Museum and we now have a good idea of the harm- 
less and dangerous species and where they breed and develop. 
It is the information gained by the work of entou ologists 
that has enabled the authorities dealing with the sanitary 
conditions of infested areas to fight the fever mosquitoes, 
and through their destruction banish or greatly reduce the 
ravages of yellow and other malarial fevers. 
There are many examples of this in the work carried 
out by the United States sanitary officers in New Orleans 
where, in the earlier outbreaks of the yellow fever epidemics 
in 1853, with a population of 130,000, New Orleans lost 8,000 ; 
in 1858 over 5000 perished, and in 1878 there were 4000 died. 
_ Under present conditions, where all water tanks are covered 
and all stagnant water treated with oil, or drained away, 
yellow fever as an epidemic is a thing of the past. The same 
