544 _ Prof. E. A. Minchin. Report on the — [Aug. 17, 
vagina. The female system of organs is considerably modified from the 
condition usually found in insects, in relation to the fly’s peculiar method of 
reproduction. 
The ovaries are reduced to a single pair of ovarian tubes or ovarioles, 
one on each side of the body (figs. 6 and 7, ov. 7., ov. 1.). Each ovariole 
shows only a small number of egg-chambers, not more than four or five. 
The lowest chamber is very much larger than any of the others, and contains 
a large ovum. When this ovum is comparatively small, the other egg- 
chambers are in a line with it (fig. 6, ov. 7.), but as the ovum grows larger 
it grows past the other egg-chambers, so that they appear attached to the 
side of the ovum (fig. 6, ov. 1., fig. 7., ov. 0, ov. 7.). 
The two ovarioles are always asymmetrical, owing to the fact that the 
ova in the lowest egg-chambers reach full growth on each side alternately, 
so that if there is a large ovum on the left, there will be a smaller one on 
the right, and vice versd. The largest ovum I have seen was from a non- 
gravid female (fig. 7, ov. 7.), and was probably nearly, if not quite full-sized. 
The two ovarioles open into the short, broad oviduct (figs. 6 and 7, od.), 
which widens out at its lower end to open into the uterus slightly behind 
the proximal end of the latter. 
At its distal-expanded end the oviduct receives right and left the two 
ducts (d. rec.) of the receptacula seminis. The latter (vec. sem.) are small 
spherical bodies of a bright orange-yellow colour, surrounded by a whitish, 
transparent envelope. Examination of the receptacula stained and mounted 
in Canada balsam shows that the clear envelope is an epithelium of large 
cells, surrounding a thick chitinous membrane which gives these organs 
their peculiar colour, and which is too opaque for the contents to be seen 
except in sections, by which method the receptacula are seen to be filled 
with spermatozoa. The two receptacula are firmly attached to one another. 
From each comes off the slender white duct, shghtly convoluted. The ducts 
are perfectly distinct from one another, and open, as described above, into 
the lower end of the oviduct. 
Immediately below the opening of the oviduct into the uterus, a small 
tube debouches into the latter by a median dorsal aperture. This is the 
common duct of the uterine glands (figs. 6 and 7, ¢.d.gl.). After a short 
course it branches right and left into tubes, which branch again repeatedly, 
forming a great number of glandular tubes, which differ markedly in the 
gravid and the non-gravid condition. In the latter state the gland-tubes 
are relatively few and very slender. In the gravid condition, on the other 
hand, the tubes are very numerous, forming a tightly packed mass filling 
up the posterior end of the abdomen, and requiring to be pulled away to 
