494 TEE DIGESTIVE APPABATUS IN MAMMALIA. 



surface, it is in order that the reparative materials dispersed in the alimentai^ 

 mass may not escape the absorbent action of that surface, and may be the more 

 effectually brought into contact with it. We have this exemplified in Ruminants ; 

 owino- to their double mastication, and the triturating action of the omasum, 

 their food arrives in the true stomach more comminuted and better attenuated 

 than in the Horse ; the mass, more finely broken up, retains less of the assimilable 

 and reparative matters, and these are more easily taken up by the absorbing 

 surface ; as a necessary consequence, the intestinal tube, although longer than 

 in Solipeds, is far from offering the same capacity. 



Analogous considerations explain the reason for the intermediate conformation 

 of the digestive canal in Omnivorous animals. 



There is, then, an admirable correlation between the conformation of the 

 digestive tube and the nature of the substances which form the basis of the 

 alimentation of animals ; and this harmony is equally apparent when the stomach 

 and intestines are compared with the other apparatus of the economy, and with 

 the natural habits and instincts of creatures. So it is that an animal furnished 

 with an ample stomach and narrow intestine, will have shai-p teeth and claws 

 to tear its prey, strength and agility to capture it, and will also possess sanguinaiy 

 instincts ; while another, with its gastric surface greatly diminished, will have 

 intestines as developed in their length as in their capacity, and be distinguished 

 by its peaceful habits, the absence of aggressive claws, and its dental apparatus 

 arranged for crushing and grinding its food — and so on. 



Organs annexed to the Abdominal Portion of the Digestive 



Tube. 



These organs are tliree in number : two glands — the liver and pancreas, which 

 pour into the small intestine two particular fluids, the bile and pancreatic juice ; 

 and a glandiform organ, the spleen, remarkable for its numerous vascular con- 

 nections with different organs of the digestive apparatus, and which for this 

 reason deserves to be studied with it, although it is doubtful, if not improbable, 

 that it has anything to do with digestion. 



Preparation. — These tliree organs can readily be studied after removing tlie intestinal 

 mass, us indicated at page 471. In order to examine the details of their organization with 

 more fucility, it would be well to detach them altogether, with the diaphragm and kidneys, and 

 to lay out the whole on a table. (To study the relations of these three organs with those of 

 the abdoniiiial cavity, it is advisable to place the subject on its sternum, after removing the 

 intestines, and to detach the posterior part of the body at the loins.) 



1. The Liver (Figs. 293 to 298) 



Situatioji — Direction. — This organ is situated in the abdominal cavity, to the 

 right of the diaphragmatic region, and in an oblique direction downwards and 

 to the left. 



Weight. — The weight of the healthy Hver iu a middle-sized horse, is eleven 

 pounds. 



Form and External Surface. — Removed from its connections with the neigh- 

 bouring organs, and viewed externally, it is seen to be flattened before and 

 behind, irregularly elongated in an elliptical manner, thick in its centre, and thin 

 towards its borders, which are indented in such a manner as to divide the organ 

 into three principal lobes. This configuration permits it to be studied in ttvo 

 (aces and a circumference. 



