390 
Amongst these I have not found B. orientalis ; and yet, as 
far as my observations go, owing to the large size and number 
of the corpuscles and the absence of dark pigment from the 
vessels of the wing, the circulation is here to be observed to 
more advantage than in any other insect. Insects are rather 
troublesome to tie down, and B. orientalis is particularly wild 
and difficult to keep quiet.1 The small apparatus (fig. 1) will 
be found very convenient for fastening this insect for exami- 
nation. To make it, a shallow rectangular box of the size of 
the figure should be taken, and filled with wet plaster of 
Paris, and into the upper surface of this, and near the edge, 
as seen in the figure, a dead blatta should be pressed down. 
When the plaster is set the insect should be pulled out, and 
a rectangular hole cut through the plaster slab opposite the 
impression. 4, a are strips of paper glued on to the plaster, 
covering up the immediate front and hind portions of the im- 
pression, and also serving to hold in position a thin glass 
which covers the rectangular hole. 
The Blatta to be examined is placed in the impression in 
the plaster, with his head under the front paper band and his 
tail under the hind one. 6 is a loop formed of a bent pin, 
with its two ends driven horizontally into the plaster. To it 
are attached two pieces of cotton, which are passed over the 
body of the insect, involving the wings not under examina- 
tion, but leaving the others free, which are brought be- 
tween the edge of the thin glass and the animal, and beneath 
the slab, to be fastened firmly to c, ¢, similar pins to Jb. 
This binding will generally suffice to hold the Blatta quiet ; 
but it may be necessary to pass another cotton from e round 
the thorax under the slab and back. The front wing is now 
to be drawn forward, and may be fastened by means of a 
stout pin; or a piece of cotton may be tied round its lip, and 
may be strained to the pin e. The very tip of the hind 
wing should now be caught up in a loop of cotton and firmly 
fixed, and by straining this cotton more or less to the pin d, 
the whole hind wing will be fully expanded over the thin 
glass and rendered ready for examination. 
The corpuscles in Blatta are so large that the circulation 
may readily be seen with a high power of a simple dissecting 
microscope. This is the most convenient method for making 
out the general direction of the currents in the wing. But 
with the wing fastened in this way it is quite easy to bring a 
Hartnack’s No. 7 to bear on it. If an insect be carefully 
tied, the circulation may be observed in action for as long as 
1 N.B.—I have tried curare, but found that it had no effect on Blatta, 
even when used in a very concentrated form. 
