ZOOLOGICAL EXERCISES. 
of the intestine, with some narrower folds of the: 
salivary glands, and the pinkish white (yellow in 0O- 
cela) malpighian tubes. On each side of the base of 
the abdomen lies a large silvery white air sac. 
5. Fasten the animal to the cork by two pins through the 
integument of the abdomen in front of the reproduc- 
tive organs. Cover with water. Turn back the re-. 
productive organs, cutting the tracheze which hold 
them down, over the apex of the abdomen, and pull 
the alimentary system over to one side. Examine 
the parts in situ. The two oviducts, or vasa defer- 
entia, join together, and open in front of the anus. 
In the female notice the three black spots, two on the 
right side and one on the left, on the vagina. These 
are the spermathecee. Trace the intestine to the 
thorax. 
6. Open the thorax by cutting all round it, and remove 
the dorsal portion of the integument. A large mass. 
of dorsal thoracic muscles, lying longitudinally, will 
be seen. Examine a portion with the quarter objec- 
tive. They are made up of loosely aggregated 
bundles of fibres, which are not striped. Notice the 
numerous trachez penetrating them. With the for- 
ceps and a needle remove these muscles bit by bit, 
and trace up the alimentary canal to the head. This 
portion is the stomach, but it is not much broader 
than the intestine. On either side of the stomach 
lie coils of the salivary glands, not easy to make out 
among the muscles. 
7. Alimentary system.—Cut through the stomach ; de- 
tach the last two segments of the abdomen, and 
remove to a glass slide the alimentary and reproduc- 
tive systems. Cover with water, and with a fine 
