xi PRACTICAL DIRECTIONS 545 



ping a cloth round it soaked in 3 per cent, formaline or strong 

 methylated spirit and placing it in a closed vessel. 



D. Dissection of the abdomen. 



I. Once more pin the animal down, ventral side upper- 

 most, and make an incision along the middle line of the 

 abdominal muscles from the xiphisternum to the pelvic 

 symphysis, so as to open up the abdominal cavity. From 

 the anterior extremity of the incision make transverse cuts, 

 and turn back the flaps of muscle. 1 Note : 



1. a, The peritoneum ; b, the diaphragm, with its muscles 

 and central tendon ; c, the pink lungs, seen through the 

 latter : make a small aperture :n the diaphragm on one side 

 of the median line and note the collapse of the corresponding 

 lung. 



2. a, The liver, stomach, small intestine, ccscum, colon, and 

 rectum (pp. 512-516) ; b, the urinary bladder ; c, the scrotal 

 sacs in the male ; and by turning aside the intestines d, 

 the kidneys ; in the female e, the ovaries and midiicts 

 (varying much in size according to age). 



3. a, The characters and relations of the lobes of the livtr 

 (compare Fig. 137), and the folds of peritoneum which attach 

 the liver to the diaphragm ; b, the gall-bladder ; e, the 

 gullet, and its entrance into /, the stomach (note its cardiac 

 and pyloric portions) ; g, the spleen. 



4. a, The parietal and visceral layers of the peritoneum 

 and the various subdivisions of the mesentery; b, the 

 U-shaped duodenum, passing into the ileum, and the 

 connection of the latter with the proximal end of c, the 

 ceecum, at the distal end of which is the vermiform 

 appendix, while proximally it passes into d, the colon, 

 continuous with e, the rectum, which enters the pelvic 

 cavity to open by the anus. 



II. Turn over the stomach to the animal's right side and 

 make out 



i. a, The postcavalvein, passing from the pelvis forwards, 

 near the ventral surface of the backbone, through a notch in 

 the liver to the diaphragm ; b, the dorsal aorta, running 

 partly above, partly alongside, the postcaval ; c, the cceliac 

 artery, given off from the aorta about an inch posteriorly to 

 the diaphragm trace its main branches ; d, the anterior 



1 You will very probably notice a number of transparent, 

 rounded vesicles, about ^ inch in diameter, in the abdomen. These 

 are tape-worms (phylum Plaiyhelminthes, p. 412) in the encysted 

 stage, which develop into the adult form when swallowed by a dog. 



