port, namely ships, that this insect has assumed such a worldwide 
distribution, as shown in the following list of localities where it has 
been recorded. 
This method of transportation was great in the old days of 
sailing ships, for the Mosquitoes we know breed in the water in 
the tanks carried for drinking purposes. At the present day distri- 
bution is going on, but perhaps not to the same extent, as there is 
little opportunity for them breeding, and the adults, although they 
can live for considerably over a month, are much more susceptible 
to climatic changes than the ova, larve and pupe. That the adults 
can travel long distances we know, as long as they are in a warm 
climate, but if they have to round Cape Horn or through any 
cold area, there is not the same possibility of their surviving in 
the adult stage as in the larval, pupal or desiccated egg stage. 
It is in this respect that the opening of the Panama Canal may 
mean a serious menace to life and trade in the East. 
We see from what BALFOUR and others say, that swarms of 
Stegomyia fasciata fly on board ship, and can be carried great dis- 
tances in warm climates. The opening of the Panama Canal will bring 
ships direct from the chief endemic center of yellow fever and 
the chief habitat of Stegomyia fasciata (its only carrier) along a 
line favourable to the insects (fig. 1). 
It will be only 12 days for a ship leaving the Panama Canal to 
get to the Sandwich Islands, and 23 days on to the Philippine 
Islands. A Stegomyia fasciata may live 47 to 50 days, and may 
thus reach the Philippines direct from the endemic centre of yellow 
fever alive. 
A case of yellow fever occurs on board ship 3 to 4 days after 
the patient is bitten by the Gnat. In 12 days the organism of 
yellow fever migrates from the Stegomyian stomach to the sali- 
vary glands. Then the Gnats can inoculate at intervals of 3 days 
for a considerable time. When these infected Gnats come to 
port they fly on land, bite people, and in this way yellow fever 
breaks out. The insect is perhaps already living there, probably in 
numbers, and thus an epidemic of yellow fever is brought about. 
It may not occur as a native insect, but flies to land and lives a 
certain time. 
That this has been the cause of outbreaks of yellow fever we 
know from the outbreak at Swansea, when there were 30 cases and 
17 deaths in 1875. The same boat that brought the yellow fever 
