No. 2.] BLATTA AND DORYPHORA. 309. 
When about to form the capsule, the female Alatta closes the 
genital armature, and the two folds of the white membrane 
which lines the odthecal cavity close vertically in the middle 
line. Then some of the contents of the colleterial glands are 
poured into the chamber and bathe the inner surface of the 
posterior wall. The first egg glides down the vagina from 
the left ovary, describes an arc, still keeping its germarium pole 
uppermost, after having pressed the micropylar area against the 
mouth of the spermatheca, passes to the right side of the back 
of the chamber, and is placed perpendicularly two-thirds to the 
right of the longitudinal axis of the insect’s body. The next 
egg comes from the right ovary, describes an arc to the oppo- 
site side of the body, decussating with the path of the first egg, 
and is placed completely on the left side of the median line. 
The third egg comes from the left ovary, and is made to lie 
completely on the right side of the median line: and so the 
process continues; the ovaries discharging the eggs alternately, 
and each egg describing an are to the opposite side of the cap- 
sule. In females killed during oviposition each oviduct will be 
found distended with eggs, often two or three end to end, in- 
creasing the length and breadth of the lumen to an abnormal 
degree. Gentle pressure of the female’s abdomen between the 
thumb and finger will sometimes cause the insect to oviposit 
a few eggs, the paths of which can be seen to decussate. 
The o6thecal chamber soon becomes too small to contain all 
the constantly accumulating eggs, so the anal armature opens 
and allows the end of the capsule to project. A raised line, the 
impression of the edges of the white membrane, runs down the 
end of the capsule. The last egg deposited comes from the right 
ovary and lies two-thirds on the left and one-third to the right 
of the median line. Thus the first and last eggs laid lie with 
their greater bulk on opposite sides of the median vertical plane 
of the capsule, and serve to commence and close the series and 
round off both ends of the capsule. Owing to their being 
crowded up against the walls of the capsule, they acquire quite 
a different shape from the remaining symmetrically and alter- 
nately deposited ova. They develop normally, however, the 
embryo appearing on the inner obtuse edge. As soon as 
the last egg is laid, a further discharge from the colleterial 
glands spreads over the vaginal or anterior wall of the cavity, 
