250 C. T. BRUES, 
larval life, when the reproductive system is in a very rudimental con- 
dition, it will be well to consider the two together. 
In the very youngest larvae (0.6 mm long) I have not been able 
to distinguish the female sexual rudiments with any degree of certainty. 
It is difficult in these small specimens to make out anything except 
the alimentary tract and nervous system which together occupy almost 
the entire body space available. Most probably the ovaries are small 
and represented by a series of cells forming a lateral mass on each 
side of the alimentary tract in the posterior half of the body. They 
are more or less concealed amongst the broken down muscular tissue 
which remains as a relic of the triangulin stage. 
In somewhat older larvae (1.5—2.0 mm long) the ovaries if they 
may be properly so called, can be seen on each side of the intestine, 
extending from the base of the first abdominal segment to the ante- 
penultimate segment. This portion evidently corresponds to the egg 
tubules, although they are much modified. Instead of separate tubules 
containing a series of eggs, the tubules are obliterated except as a 
very irregular epithelium which is applied rather closely to several 
strings of primitive eggs. I call these structures primitive eggs to 
distinguish them from the definitive eggs, several of which arise from 
a single primitive egg. The primitive eggs (see Fig. 1) are arranged 
‘rather irregularly, but seem to form into about two or three more or 
less sinuous strands on each side of the intestine. At places the 
strands may be separate and at others enclosed in a common envelope. 
Beyond the base of the penultimate abdominal segment no eggs are 
present, but there is a continuation of the tubules to form an oviduct. 
The presence of the rudiment of an oviduct and vagina is rather re- 
markable and does not in the least foreshadow the peculiar manner 
in which the reproductive system will continue its further development. 
Every one of the eggs contained in the ovaries of the same animal 
is in exactly the same stage of development; thus we cannot find 
younger eggs in the anterior parts of the ovaries as is usual in in- 
sects. This condition persists throughout the entire development, all 
the embryos in one female hatching at practically the same time. 
The egg, exclusive of its follicular covering, is composed of a 
mass of similar conical cells, radially arranged, with their apices 
directed inwards. A very small cavity exists at the center of this 
spherical mass, although it is almost absent in many eggs. The cells 
have large nuclei with deeply staining nucleoli. 
The ovaries remain in this condition for a considerable length of 
