ON THE SUBJECT OF PLAGUE 
873 
2. When fleas are present, the epizootic, if it does 
start, varies in severity and rate of progress according to 
the season, and this season corresponds to that of the 
plague epidemic. 
3. An epizootic of plague may occur in a godown con- 
taining infected fleas without direct contact of healthy animals 
and infected animals. 
4. In an infected godown, the infection is effective in 
proportion as the test animals are accessible to fleas. 
5. Infection can take place without any contact with 
contaminated soil. 
6. The experiments exclude aerial infection. 
7. The general conclusion was that fleas, and fleas alone, 
were the transmitting agents of infection. 
Construction of Godowns . — These were six in number, and 
were built in a row. The walls were of brick and mortar and 
the floor of cement, and so were rat proof. The rooms were 
of the same size, and the essential difference was in the 
construction of the roofs. 
In the case of rooms Nos. 1 and 2, the roof was of 
ordinary, semi-cylindrical country tiles, which afford a very 
good harbourage to rats. 
Immediately underneath this roof was a wire netting, 
carried on a wooden framework, which was let into the walls 
with cement ; the idea being to allow a free passage to the 
rat flea, but not to the rat. 
The roofs of rooms Nos. 3 and 4 were similar, but built 
with the flat Mangalore tiles. These, though they afford 
harbourage to rats, do not do so to anything like the same 
extent as the country tiles. 
The third set of two rooms had corrugated iron roofing, 
which should have been rat and flea proof. As a matter of 
fact they had to make these last rooms with concrete, as they 
found that somehow or other fleas did actually find their way 
through the corrugated iron roof — probably by way of cracks 
in the cement. 
The difference in the construction of the roofs is of such 
a nature that the natural supply of fleas, depending as it does 
on the number of rats in the roofs, varies in the different 
