202 VERTEBRATES 



exit from it, and make a drawing of it (X/4). From the 

 caecum onward tiie alimentary tract is called the large in- 

 testine. Note its sacculated form in the upper part, becom- 

 ing smoother in the lower. The lower part of the canal 

 is called the rectum. Measure the length of the entire ali- 

 mentary canal, approximating as nearly as possible the 

 length of the esophagus, and make a diagram showing and 

 naming the different parts of the entire system. Tie the 

 lower part of the alimentary canal and sever it at the anus. 

 Remove the canal, tie the duodenum in two places about 

 an inch apart. Cut out a small section between, and study 

 the structure of the canal. Find the outer serous coat, the 

 inner muscular ring, and the mucous lining. What use 

 has each? This illustrates the structure of the entire canal. 

 Draw an end view (X2). If alimentary canal were shorter, 

 how would it affect digestion? If longer? What then de- 

 stroys the bilaterality of the abdominal viscera? Make a 

 list of the parts of the alimentary canal, and give the prob- 

 able uses of each. (This item is optional and requires a 

 lecture by the teacher or the use of reference books on 

 physiology. ) 



(8) The alimentary canal having been removed, the 

 urinary and the reproductive systems are plainly shown. 



(a) If the specimen is a female, note the ovaries and the 

 oviducts converging toward the dorsal opening. 



(b) If it is a male, find the testes and the vas deferens. 

 Find the kidneys in the dorsal part of the abdominal 



cavity. Note their relative position. Are they opposite ? Is 

 there any advantage in their arrangement? Remove the 

 fat from them and trace the urinary ducts down to the 

 bladder at the pelvic arch. Draw the renal and reproductive 



