Pisces. 75 



6. Turn the liver to the right, gently tearing away its threadlike 

 attachments. This uncovers a pinkish sac, the stomach. Pass a 

 probe back from the mouth and wide gullet into the stomach to 

 determine its shape and extent. Such a stomach as that of the 

 perch, ending blindly at the posterior end, and with the intestine 

 arising from near its anterior end, is said to be cecal. Sometimes 

 the posterior end of the stomach of the perch is found turned in, 

 like an inverted glove finger, occasionally to such an extent as 

 to be seen projecting from the gullet into the mouth. Observe a 

 white thread, the vagus nerve, distributed over the side of the 

 stomach. 



7. Find a large tube, the intestine, arising from one side of 

 the stomach. A short distance from its origin, the intestine has 

 several short, blind branches, the pyloric ceca. How many are 

 there and how are they arranged ? Make a small hole in the end 

 of one cecum ; insert the point of a blowpipe and inflate to show 

 the intestine and ceca. 



8. Just beyond the ceca, on the posterior surface of the liver, is 

 a thin-walled sac, of a greenish or yellowish color, the bile sac. 

 If it contains bile, press on it to show the course of the bile duct 

 to the intestine. When empty, it often has a wormlike appear- 

 ance. Snip it open with the scissors, or prick it with a dissecting 

 needle to see the bile. 



9. Trace the intestine to the anus, observing that it is held in 

 place by a thin, transparent membrane, the mesentery ; observe 

 the blood tubes in it ; tear this away in following the intestine ; 

 near the intestine find a small, deep red body, the spleen. 



10. In the hinder part of the body cavity of the female is the 

 yellow, or pink, ovary (varying greatly in size, according to the 

 season). The two white spermaries occupy a corresponding posi- 

 tion in the male. In some fishes the ovary is single, in others it 

 is double. If double, the two ovaries unite in one tube, which 

 discharges the eggs, the egg tube, or oviduct. Trace the oviduct; 

 has it a separate outlet ? Sometimes the eggs, in the ovary can 

 be discerned. 



