162 ANIMAL PHYSIOLOGY. 



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body. It contains also a smaller proportion of red cor- 

 puscles than other blood, which perhaps results from a 

 portion of their contents having transuded into the serum, 

 as shown by its colour, and by the corpuscles being firmer, 

 smaller, and more nearly spherical. Lastly, the colourless 

 corpuscles are exceedingly plentiful; and it is to be noted 

 that in a diseased condition called leucocythaemia, in which 

 the colourless corpuscles of the blood are remarkably in- 

 creased in number, there is likewise great enlargement of 

 the spleen. These are the principal facts on which rest the 

 two theories generally held as to the function of the spleen, 

 namely, that it is a manufacturer of white corpuscles, and a 

 destroyer of the red. 



That the spleen is a source of white corpuscles can scarcely 

 be doubted; but that it is its special function to destroy red 

 corpuscles, is not so clear. ISTo doubt heaps of withered red 

 corpuscles have been seen in the spleen as an exceptional 

 occurrence; but it is plain that there is an action exercised 

 on all the red corpuscles, and it seems very possible that the 

 object of that action is restoration rather than destruction. 

 A very curious circumstance, which by no means makes the 

 function of the spleen more comprehensible, is that the whole 

 organ may be extirpated, not only without death ensuing, 

 but without any inconvenience resulting. It is obvious, 

 however, that this is more explicable on the supposition that 

 the spleen is one of many structures which produce blood 

 corpuscles, than if we consider it as the sole agent of their 

 destruction. 



122. The Liver (figs. 57 and 78). -The liver is much the 

 largest gland in the body, between 3 and 4 Ibs. in weight, 

 and of remarkable complexity, both of structure and func- 

 tion. Its most obvious function is to secrete bile; but the 

 bile is secreted less for the sake of its utility in digestion, 

 than as a product resulting from certain complicated pro- 

 cesses of blood-purification. 



The liver lies beneath the diaphragm, with the greater 

 part of its bulk on the right side, under cover of the ribs, 

 and from its position is the organ most liable to compression 

 and injury by tight-lacing. It has a right and left lobe, and 

 is, in fact, a bilateral organ in all vertebrate animals. It even 



