LARV/ IN BRACKISH WATER 289 
days; Taylor of Havana, places it at nine days. As already mentioned, Dupree 
and Morgan, succeeded in obtaining imagos after from six to eight days. 
At Para, Goeldi conducted a number of experiments on the rapidity of de- 
velopment of the yellow-fever mosquito. The duration of the entire cycle, from 
the date of oviposition to the emergence of the imagos, showed a minimum of 
twelve days and a maximum which was indefinite and almost unlimited, accord- 
ing to the season of the year and the dearth or abundance of food. He ob- 
served one case in which a male emerged only after fifty days, and other cases 
where with the same number of days there were still larvae and pupe. 
The French observers determined a distinct relation between temperature and 
the rate of development. At Rio in the most favorable season, when the night 
temperatures were from 26° to 27° C. (79°-81° F.) and the day temperatures 
from 28° to 31° C. (82°-88° F.), they observed that some of the larve of 
calopus reached the pupal stage seven days after the hatching of the eggs, and 
the adult condition on the ninth day, and generally most of the larvee from the 
same laying of eggs produced imagos about the tenth day. They found that 
when this rapid breeding occurred it was necessary that the egg as well as the 
larva should have had the right temperature and the egg a rapid incubation. 
The temperature being lower the evolution naturally becomes longer, and at 
Petropolis, with a night temperature lower than 22° C. (72° F.), they found 
the larve taking from forty to sixty days to reach the pupal state, and from three 
to five days longer before the perfect insect issued. Ordinarily, according to 
their observations, the pupal stages last only from thirty to fifty hours. They 
found that the larvee do not perish at a temperature near the freezing point, but 
they grew very slowly and took an indeterminate time to become adults. 
The French investigators showed that the development of this species is 
possible in brackish water, but that soapy water is very destructive to them. 
They proved that in sea-water they perish quickly; that this is not true when 
sea-water is mixed with fresh water. In one of their experiments a female, 
placed in a tube containing five-sixths fresh water and one-sixth sea-water, laid 
its eggs as under normal conditions. These eggs hatched at the end of four days, 
and the larve, reared in a jar containing the same water, reached the pupal 
condition on the eleventh day and the perfect condition on the thirteenth day. 
The same result was reached when larve were placed in brackish water con- 
taining one-fifth sea-water and four-fifths fresh water, but two young larve 
placed in brackish water containing one-third sea-water perished at the end of 
a few hours. 
RESISTANCE OF LARVZ TO ADVERSE CONDITIONS. 
“The Brazilian investigators made an extensive series of experiments to de- 
termine the effect of brackish water of different degrees of salinity. They found 
that in a mixture of 30 per cent sea-water with 70 per cent fresh water the larvee 
transformed to imagos {n a normal manner, although development was retarded. 
They found larve of calopus in nature in brackish water containing 35 per cent 
sea-water. With 40 per cent sea-water the larve still survived and a few pro- 
