68 ORGANS OF DIGESTION. 



foetal state, are of an intermittent kind throughout life, the spleen 

 may, therefore, be considered a vicarious organ for it during 

 the whole period of existence, receiving its blood during the 

 continuation of uterine life, and, in the intermission of action, 

 during common life. The spleen is, therefore, an organ useful 

 to the fo2tal and to the perfect state, and we, consequently, 

 never see it in the collapsed and dwindled condition of the thy- 

 mus gland, and renal capsule* 



The same reasoning which applies to the spleen, will also 

 apply to the Thyroid Gland: the latter may be considered as 

 executing for the salivary glands during foetal and perfect ex- 

 istence, what the spleen does for the liver. For it is ascer- 

 tained, that the salivary glands are inactive during foetal exis- 

 tence, have only an intermittent action during perfect life, and. 

 therefore, probably stand in need of a supplementary organ 

 during their periods of inactivity. 



SEC. III. OF THE PANCREAS. 



The Pancreas (Pancreas) secretes saliva, and is the largest 

 of the salivary glands. It is fixed in the lower back part of 

 the epigastric region; and extends horizontally across the spine, 

 being separated from it by the lesser muscle of the diaphragm. 

 It is connected to the spleen on the left; at its right extremity 

 is surrounded by the curvature of the duodenum ; is bounded 

 in front by the stomach, which conceals it ; and is placed be- 

 tween two laminae of the mesocolon. 



The pancreas is about six or seven inches long, two wide, 

 and flattened before and behind. Its figure would be repre- 

 sented by a parallelogram, were it not that its right extremity 

 is enlarged considerably into a head or tuber, to which Wins- 

 low gave the name of the Lesser Pancreas. The anterior 

 face of this organ is turned obliquely upwards, and is covered 

 by the superior lamina of the mesocolon. The posterior face 

 looks obliquely downwards, and is in contact with the aorta, 

 the vena cava ascendens, the superior mesenteric vessels, and 

 several nerves: along the superior margin of this face exists 

 a long superficial fossa, occupied by the splenic artery and 

 vein. 



