OBSERVATIONS. 



ject. The association of a well defined abdominal oeso- 

 phagus with any increase in size of the spigelian lobe is 

 worthy of note. In the human liver, in addition, the 

 ventral position of the inf. v. cava and the ductus venosus 

 are factors helping to retain a spigelian projection. 



U union Liver and Its Abnormalities. 



Occasionally, human livers are met with presenting 

 curious fissurings and lobulations, which are classified as 

 abnormalities, but the significance of which is explained 

 by a study of Australian mammals. In what may be re- 

 garded as a typical mammalian liver a primary division 

 into five lobes may be recognized, namely, the mesial or 

 cystic, lodging the gall bladder, which is separated on 

 either side from the right lateral lobe and left lateral lobe 

 by the right and left lateral fissures, and on the visceral 

 surface of the right lateral lobe, as is well shown in 

 Platypus, we have projecting the lobus spigelii and 

 dextrally the larger free caudate lobe. The spigelian 

 lobe reaches its maximum development in the Kangaroo, 

 where it dips down within the lesser sac in the interval 

 between the right and left portions of the great stomach, 

 being grooved for the passage of a large abdominal oeso- 

 phagus, 10 to 12 cm. in length. The caudate lobe, on the 

 other hand, though well defined in Platypus, and 

 especially in Echidna, may be regarded as non-existent in 

 Kangaroo and Wombat. In the Echidna it is seen to be 

 largely an accommodation effect for the upper pole of the 

 right kidney and adrenal. With comparative fixation 

 of duodenum and pancreas and unification of the organ, 

 a more limited relation of kidney to liver is seen, with 

 disappearance of the right lateral fissure. Amongst the 

 members of the Australian fauna, the gall bladder forms 

 a separation of the mesial or cystic lobe into two primary 



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