PARTS OF ANIMALS, IV. ii. 



animals have no gall-bladder at all, such as the horse, 

 the mule, the ass, the deer, and the roe ; and the 

 camel has no distinct gall-bladder, but what would 

 better be described as consisting of small biliary 

 vessels. There is no gall-bladder in the seal, nor 

 (among sea-animals) in the dolphin. Sometimes in 

 the same group there are some animals Λvhich look as 

 if they have one, and some as if they have none" : 

 This is true of the Mice ; and also of the human 

 species, as in some individuals the gall-bladder is 

 placed against the liver and is obvious ; while in some 

 it is missing. The result of this has been a dispute 

 concerning the group as a whole. Whatever an 

 observer has found to be the condition of the indi- 

 viduals he happens to have seen, that he holds is true 

 of every individual throughout the group. The same 

 has occurred Λvith regard to sheep and goats, most of 

 which have a gall-bladder ; but, whereas in some 

 Individuals it is so large that its excessive size is 

 portentous (e.g. in Naxos), in others it is entirely 

 absent (e.g. in a particular district of Chalcis, Euboea). 

 A further point, already mentioned, is that in fishes 

 the gall-bladder is separated from the liver by a good 

 distance. Moreover, it is safe to say that Anaxa- 

 goras's school is wTong in holding that the gall-bladder 

 is the cause of acute diseases : they say that when it 

 gets too full it spurts its liquid out into the lung and 

 blood-vessels and sides. This must be vvTong, because 

 nearly everyone who suffers from these affections 

 actually has no gall-bladder, and this would be proved 

 if they were dissected. Besides, there is no com- 

 parison between the amount of bile which is present 

 in these ailments and that which is emitted from the 

 gall-bladder. No ; it seems probable that, just as the 



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