82 
ZOOLOGICAL EXERCISES, 
mesothorax. Gently push the cesophagus on one 
side with a bent needle and observe the salivary 
ducts running forward in the prothorax. The two 
unite into a single duct, which opens inte the mouth 
beneath. Cut the intestine close to the anus and 
turn it forward, cutting the trachez when necessary. 
Cut the cesophagus near the head, and remove the 
alimentary canal to a glass slide. Lay it out with a 
camel-hair brush and water. Brush out the mal- 
pighian tubes. They are very numerous, and open 
into the intestine about half-way between the pyloric 
end of the stomach and the anus. The pyloric end 
of the stomach and the duodenum are surrounded by 
a thick yellowish-brown cellular mass, the liver. 
Examine a portion with the microscope, and then 
gently remove the remainder. ‘The stomach passes 
suddenly into the anterior portion of the intestine— 
the duodenum. Examine a portion of the malpighian 
tubes with the quarter objective. Lay open the 
stomach and cesophagus with the scissors, and wash 
away the contained food with a brush. Examine a 
portion with the microscope. Notice the numerous 
rows of small teeth in the cesophagus and stomach, 
pointing backward, and the large thorn-like teeth in 
the stomach. Also notice the longitudinal and trans- 
verse bands of muscular fibres. The fibres are trans- 
versely striated. 
6. Reproductive system, The ovaries are two, one on 
each side. They are pectinated, the short unilocular 
pedunculated ovarian tubes being inserted on the 
outer side only of the oviducts. Trace the oviducts 
down. They unite to form a vagina which opens in 
the seventh segment. Opening into the vagina 1s 4 
