IV. I — IV. 2. '93 



body being long and narrow, its contents are as it were moulded 

 into a similar form, and thus come to be themselves elongatedJ 



All animals that have blood possess an omentum, a mesentery,^ 

 an intestine with its appendages, and, moreover, a diaphragm 

 and a heart ; and all, excepting fishes, a lung and a trachea. The 

 relative positions, moreover, of the windpipe and the oesophagus 

 are precisely similar in them all ; and the reason is the same as 

 has already been. given.^ 



(Ch. 2.) Almost all sanguineous animals have a gall-bladder. 

 In some this is attached to the liver, in others separated from 

 that organ ^ and attached to the intestines, being apparently in 

 the latter case no less than in the former an appendage of the 

 lower stomach.2 It is in fishes that this is most clearly seen. 

 For all fishes-^ have a gall-bladder ; and in most of them it is 

 attached to the intestine, being in some, as in the * Amia, united 

 with this, like a border, along its whole length. It is similarly 

 placed in most serpents. There are therefore^ no good grounds 

 for the view entertained by some writers, that the use of the 

 gall-bladder is to give rise to certain sensations. They say 

 that its final cause is to affect that part of the soul which is 

 lodged in the neighbourhood of the liver, and that it induces 

 a gloomy or a cheerful disposition,' according as it irritates this 

 or leaves' it alone. But this cannot be. For in some animals 

 there is absolutely no" gall-bladder at all, in the horse for instance, 

 the mule, the ass, the deer, and the roe ; and in others, as the 

 camel, there is no distinct bladder," but merely small vessels 

 that bear some resemblance to one.^ Again there is no such 

 organ in the seal, nor, of sea-animals, in the dolphin.' Even 

 within the limits of the same genus, some animals appear to 

 have and others to be without it.^ Such for instance is the 

 case with mice ; such also with man. For in some individuals 

 there is apparently a gall-bladder attached to the liver, and in 

 others none at all. This explains how the existence of this 

 part in the whole genus has been a matter of dispute. For 

 each observer, according as he has found it present or absent 

 in the individual cases he has examined, has supposed it to be 

 present or absent in the whole genus. The same has occurred 

 in the. casie of sheep and of goats. For these animals usually 

 have a gall-bladder ; but, while in some it is so enormously big as 

 to appear a monstrosity, as is the case in Naxos, in other instances 

 677a. 



