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Stegomyia fasciata 
grown within 7 days, and two male specimens were reared within 10 days, 
the other three took longer, but the most backward larvae had pupated 
by the 9th day. 
Over 13 months. On 12 January, 1917, a single larva emerged from a batch of about 
1000 eggs. It hatched within 24 hours of immersion and pupated within 
7 days; a male specimen was reared within 10 days. 
On 15 January, 1917, some 14 to 15 months after laying, the re¬ 
mainder of the eggs (upwards of 1000) were immersed, but all failed to 
hatch. 
It is of course possible that the temperature conditions were un¬ 
favourably low during the storage of the eggs for a race of the insect 
occurring in West Africa. Although none of the eggs stored out of 
water by Bacot (1916) in Freetown retained their vitality for more than 
8-9 months, it might be objected that this was owing to the humidity 
factor being unfavourable and that in a saturated atmosphere a higher 
temperature than that of the cellar used in this experiment would allow 
of an extension of the period of viability. As against this, the facts 
concerning the period of viability when immersed must be considered. 
The longest period of dormancy noted in regard to submerged eggs 
under natural conditions (in West Africa) was 5 months, and although 
in an incubator at 24° C. (75° F.), in London, I have had several equally 
long records of dormancy, and one of 7 months, the conditions were 
admittedly unnatural in that the eggs had been externally sterilized 
and then placed in sterile fluids. 
Mitchell’s record (1917, p. 26) relating to the survival of the eggs 
when immersed in water for over a year, is unfortunately unaccompanied 
by any details that suggest close observation. In another passage 
(p. 148) this author places the limit at 9 months, while the looseness of 
phraseology as indicated by the statement “as the single eggs will 
resist drying almost indefinitely” leaves one in doubt as to whether 
the periods mentioned are the result of exact observation or conclusions 
based on general experience. 
I venture to call the attention of American investigators to the 
desirability of further evidence on this point. Though I am prepared 
to find that the period may be longer than my evidence shows, it seems 
to me possible that the African and American races of S. fasciata —to 
suggest no smaller division—may differ considerably in constitution. 
Personally I am inclined to consider that the cool conditions did not 
affect the viability of the eggs experimented with and that so far as 
eggs of West African origin are concerned, the extreme period of 
viability of eggs stored out of water may be taken to be about a year. 
