DISSECTION OF THE ABDOMEN. 



333 



vessel. Its branches enter at the concave border of the spleen, and 

 carry with them sheaths derived from the fibrous tunic. These 

 branches reduce themselves by division, 

 and the smaller bi-anches are remark- 

 able in having the outer coat formed of 

 lymphoid tissue Here and there this 

 lymphoid tissue forms distinct swellings 

 developed either uniformly ai-ound the 

 arteries, or more or less to one side. 

 These are the Malpighicm bodies of the 

 spleen. The arteries terminate in tufts 

 of capillary vessels in the pulp. They 

 are believed to have incomplete walls, 

 allowing their contents to escape and 

 form the pulp. The rootlets of the 

 splenic vein begin in the same manner, 

 having incomplete walls through which 

 their lumen is continuous with the spaces 

 lodging the pulp. Gradually their walls 

 become thicker and complete, and adja- 

 cent veins uniting on their course towards 

 the anterior border form the large splenic 

 vein, which is one of the main branches 

 of the portal vein. 



The Splenic Pulp possesses a supporting network of retiform connective- 

 tissue; and the meshes of this network are set with many lymphoid 

 cells like the colourless corpuscles of the blood, and with red blood 

 corpuscles, normal or in different stages of disintegration 



Cut Surface of Horse's Spleen, 

 trabecular framework. 



STRUCTURE OF THE PANCREAS. 



The pancreas is a compound tubular or racemose gland. It is com- 

 posed of lobules held together by a connective-tissue framework. When 

 the main ducts of the gland are traced backwards into the gland, they 

 are found to be formed by the imion of smaller ducts, and so on until 

 the smallest ducts are reached. These begin in the alveoli, which are 

 lined by secretory epithelium. 



STRUCTURE OF THE KIDNEY. 



The kidney is invested by a fibrous cajjsule. In health this can with- 

 out difficulty be stripped off the kidney substance, to which it is con- 

 nected only by delicate processes and vessels. If a horizontal section be 

 made from the convex border to the hilus of the kidney, the organ will 

 be seen to possess a cavity towards the hilus, termed the pe^yw, and to 



