298 ZOOTOMY. 



to the dorsal body-wall by a sheet of peritoneum, the 

 mesorectum. 



176. The passage of the ileum into the proximal end of 

 the caecum, and the exit of the colon from the same. 



177. The termination of the distal or blind extremity of 

 the cKcum in a finger-like, thick-walled process, about three 

 inches long, the appendix vermiformis. 



178. The passage of the rectum posteriorly into the pelvic 

 cavity, between the bladder and the vertebral column, to 

 open externally by the anus. 



179. The reflections of the peritoneum : its parie- 

 tal layer, or lining of the abdomen, on reaching the middle 

 dorsal line is reflected ventralwards, forming the various 

 subdivisions of the mesentery — mesentery proper, meso- 

 gaster, mesorectum, &c. — which thus consists of two closely 

 apphed layers, one continuous with the parietal layer of the ■ 

 right, the other with that of the left, side : on reaching the 

 alimentary canal the two layers diverge again and invest it, 

 forming the visceral layer or peritoneal investment of the 

 alimentary canal. 



XVIII. Turn over the stomach and intestines to the 

 animal's right side, and make out : 

 t8o. The postcaval vein, or inferior vena cava^ 



■• A rabbit is best injected for anatomical purposes -with plaster of 

 Paris (see p. 48, note). Kill the animal with chloroform or potassic 

 cyanide : as soon as it is dead, open the thorax by cutting through the 

 sternal ribs of both sides, sufficiently far froji the middle line not to 

 injure the mammary arteries {§ 250), cutting across the posterior end 

 of the sternum and turning it forwards ; slit open the pericardium, and 

 make a large incision, by a single cut of the scissors, in each ventricle : 

 all this should be done very rapidly, if possible before the heart has 

 ceased to beat, as it is desirable to get rid of as much blood as possible: 

 jjass a ligature round the aorta close to its exit from the heart, and give 

 it a single loose tie ; when the bleeding has ceased, sponge the blood 

 from the heart, and pick out any clots which may have formed in the 

 left ventricle : pass a cannula through the incision in the left ventricle 

 into the aorta, tighten the ligature and knot it firmly. By this operation 



