292 WHEELER. [Vox. II. 
Periplaneta orientalis oviposits from April to August; Blatta 
germanica, at all times during the year. The odthece of P/ata- 
modes may be collected in great numbers where the insects 
abound. After many futile attempts to open the oédthecz of 
Periplaneta and Platamodes without injuring the ova, I limited 
my study to 4latta, the egg-capsules of which may be easily 
opened by the method given below. By careful treatment of 
the thick-walled capsules of Periplaneta and Platamodes with a 
sufficiently strong solution of sodium hypochlorite, it may be 
found possible to isolate the ova in an uninjured condition. 
Specimens of Blatta germanica can be obtained at all times 
of the year from places which they haunt, and with very little 
attention will live long in confinement. The male is long and 
narrow, tapering anteriorly and posteriorly ; the female is much 
broader and flatter and uses her wings much less than the male. 
Males seem to endure the unfavorable condition of captivity 
much better than females. When it is desired to time the eggs, 
the capsule cannot be detached from the female without damage 
till it has been rotated, and during winter must be’ kept under 
a bell jar with plenty of moist blotting-paper to prevent the 
embryos shrivelling from the dryness of the air. 
The ovarian ova in all stages up to maturity were dissected 
out in normal salt solution and hardened for fifteen minutes in 
Perenyi’s fluid. They were then transferred to 70 per cent 
alcohol, which was changed several times at intervals of an hour, 
and were finally preserved in alcohol of the same strength. 
When stained with borax carmine and sectioned, the yolk retained 
none of the red stain, while the chromatin of the nucleus shone 
out as a glistening deep red spot. Perenyi’s fluid rendered the 
chorion of the mature ovarian egg pervious to borax carmine. 
Hardening in a saturated aqueous solution of corrosive subli- 
mate gave good results with young ovarian eggs. 
Oviposited eggs were killed by placing the capsules in water 
slowly heated to 80°-g0°C. The two lips of the crista of the 
capsule were then separated by the aid of fine forceps, and pieces 
of the walls torn away, till the eggs could be easily pushed out 
of the compartments formed by their choria. 
The ova thus isolated were either transferred directly through 
35 per cent (10 min.) to 70 per cent alcohol, or they were left for 
15 minutes in Kleinenberg’s picrosulphuric acid, and after re- 
