LIVER 



271 



region which possibly represents the rudiment of the liver (Fig. 219). 

 In Craniates the outgrowth develops into a large vascular and 

 glandular organ, which gives rise to bile, and remains in communi- 

 cation with the intestine by means of one or more bile-ducts x 



ED 



FIG. 217. VISCERA OF Lacerta agilis. (From the ventral side.) 



Oe, oesophagus ; M, stomach ; MD, small intestine ; ED, large intestine ; Z/, 

 liver ; GB, gall-bladder ; Pn, pancreas ; SI, urinary bladder ; Lg, Lg l , 

 the two lungs, with their network of vessels ; //, heart ; Ci, postcaval, Tr, 

 trachea. 



^Figs. 206, 209, and 216-218). It is united to the body- wall by a fold 

 of the peritoneum, and varies considerably in the number of its 

 lobes : in Mammals there may be as many as six or seven (e.g., Dog, 

 Weasel). We may nevertheless fix upon a ground-form consisting 



1 The single-lobed liver of the Lamprey undergoes a histological retrogression 

 (fatty metamorphosis) after transformation. The tubuli disappear, the cells 

 become filled with fat, and the gall-bladder and bile-duct become atrophied. 



