THE STICK INSECT, 8] 
to the cork, dorsal side up, by means of pins put in 
slanting over the thorax. Make a longitudinal, 
median incision from the end of the abdomen to the 
head. Pull the sides of the abdomen and thorax 
carefully open and fasten with two or three pins on 
each side, removing those first putin. Cover with 
water. Notice that the parietes of the body is lined 
with a pale yellow fatty mass, the corpus adiposum. 
The long cesophagus semi-transparent, and coloured 
with the food inside, extending to the middle of the 
mesothorax, slightly enlarged into a crop at the end, 
and then constricted before it passes into the stomach. 
This viscus is cylindrical and occupies the greater 
part of the metathorax ; its posterior end is hidden by 
a yellowish-brown coating. The abdomen is filled 
with the yellowish ovaries. Notice the silky white 
branching trachew. There is a large longitudinal 
trunk on each side of the alimentary canal. 
4, Turn back the ovaries, cutting, when necessary, the 
trachez. Notice the trachew going to each sprracle 
of the abdomen and thorax. The lateral trunks on 
the alimentary canal open just behind the middle 
pair of legs. Cut off a piece of one of the trachee, 
mount it in water under a thin glass cover, and 
examine with the inch objective. Place one of the 
cut ends in the field and press down the cover class 
with the handle of a needle. Observe the bubble of 
air coming out from it. Examine with the quarter 
objective and notice the spiral fibre. 
D. Alimentary system, — Notice the intestine going 
| straight to the terminal anus, and the large number 
of white malpighian tubes—renal organ — lying 
around it. Notice the white salivary clands in the 
Peay 
