290 MOSQUITOES OF NORTH AMERICA 
duced imagos. With mixtures up to 8 and 9 per cent the larve developed nor- 
mally but when the salinity was increased beyond this the larval period was 
greatly prolonged. Under these conditions larve lived for 50 days without 
transforming. One larva, in a mixture with 10 per cent sea-water, died without 
transforming after having lived 92 days. Larvee well advanced are much more 
resistant and when nearly full grown would still transform in highly saline 
water. In a proportion of 50 per cent sea-water the larve generally survived 
24 hours and those that were nearly full grown transformed to pupe. Beyond 
this the larvee only transformed when they were within one or two hours of the 
pupal stage and then only in mixtures up to 56 per cent sea-water. Of 50 larve 
placed in a mixture of 60 per cent sea-water three survived to the third day. 
The pups, when placed in pure sea-water, always produced imagos in a normal 
manner. 
These experiments are of considerable economic importance, as they show that 
the larve of calopus may, in nature, survive in water which has, through evapo- 
ration, reached a high degree of salinity. If afterwards, through rains, the solu- 
tion becomes again diluted the larvee may then develop to imagos. 
Experiments were also made with solutions of pure salt (NaCl) and it was 
found that the larve would not withstand solutions stronger than one per cent. 
Only once a larva transformed to pupa in a solution of 1.5 per cent, but in this 
case the larva was already full grown and ready to moult. 
The Brazilian investigators also experimented with corrosive sublimate. In 
the presence of 1/1000 the larva of calopus, on the average, died after one and 
a half hours and the pupe but rarely produced imagos. With 1/2000 the larve 
died, on the average, after 44 hours and the pupe produced imagos. With 
1/10000 a very few larve developed to imagos, but this only happened when 
they were in the last stage. 
At Rio de Janeiro it was found that the tanks used for washing clothes were 
favorite breeding-places of Aédes calopus. Both the French commission and the 
Brazilian investigators experimented on the effect of soap in the water on the 
larve. 
In their experiments with soap the French investigators found that larve of 
any age placed in a solution containing one-thousandth by weight Marseilles 
soap died in five minutes. In solutions of one to five thonsand and one to ten 
thousand, they lived for a time but finally died. In solutions of one to two 
hundred thousand and one to two hundred and fifty thousand, they developed 
normally. The larve bred normally in basins and tubs in which linen is cus- 
tomarily washed, because, when the soapy water remains in the tubs for some 
days, its alkalinity is greatly diminished. Peryassi experimented with common 
Brazilian washing soap. He found that larve of any age, when placed in a 
solution of one-thousandth by weight died in from six to seven minutes. Only 
when the solution was weakened to 1/200000 or less did the larvw develop in a 
normal manner. 
In apparent contradiction to this extreme sensitiveness to alkalinity are the 
observations of Agramonte, already mentioned, that the presence of wood ashes 
