24 
The larve issue from the underside of the egg masses, and are 
extremely active at birth. When first observed it is easy to fall into 
an error regarding the length of time which they can remain under 
water, or rather without coming to the surface to breathe, since, in 
striving to come to the surface for air, many of them will strike the 
underside of the egg mass and remain there for many minntes. It is 
altogether likely, however, that they get air at this point through the 
egos or through the air film by which the egg mass is surrounded, and 
that they are as readily drowned by continuous immersion as are the 
older ones, as will be shown later. 
One of the first peculiarities which strikes one on observing these 
newly-hatched larve under the lens is that the tufts of filaments which 
are conspicuous at the mouth are in absolutely constant vibration. This 
peculiarity, and the wriggling of the larve through the water, and 
Fic. 2.— Culex ounaeise Eee of larva from below at left; same from above at right—greatly enlarged 
(original). 
their great activity, render them interesting objects of study. In gen- 
eral the larvee, passing through apparently three different stages, reach 
maturity and transform to pupz in a minimum of seven days. When 
nearly full grown, their movements were studied with more care, as 
they were easier to observe than when newly hatched. At this time 
the larva remains near the surface of the water, with its respiratory 
siphon at the exact surface and its mouth filaments in constant vibra- 
tion, directing food into the mouth cavity. Occasionally the larva 
descends to the bottom, but, though repeatedly timed, a healthy indi- 
vidual was never seen to remain voluntarily below the surface more 
than a minute. In ascending it comes up with an effort, with a series 
of jerks and wrigglings with its tail. It descends without effort, but 
ascends with difficulty; in other words, its specific gravity seems to be 
greater than that of the water. As soon, however, as the respiratory 
