PARTS OF ANIMALS, II. i.-n. 



called viscera follows suit. They are all composed 

 of the same material, as they all have a sanguineous 

 character, and this is because they are situated 

 upon the channels of the blood-vessels and on the 

 points of ramification. All these viscera (excluding 

 the heart) may be compared to the mud which 

 a running stream deposits ; they are as it Λvere 

 deposits left by the current of blood in the blood- 

 vessels. As for the heart itself, since it is the starting- 

 point of the blood-vessels and contains the substance 

 \dynamis) by which the blood is first fashioned, 

 it is only to be expected that it will itself be com- 

 posed out of that form of nutriment which it 

 originates. 



We have ηολν stated why the viscera are san- 

 guineous in formation, and why in one aspect they are 

 uniform and in another non-uniform. 



II. Of the uniform parts in animals, some are The uniform 

 soft and fluid, some hard and firm. Some are ^^'^ ^' 

 permanently fluid, some are fluid only so long as they 

 are in the living organism — e.g. blood, serum, lard, 

 suet, marrow, semen, bile, milk (in the lactiferous 

 species), flesh. (As these parts are of course not to 

 be found in all animals, add to this list their counter- 

 parts.) Other of the uniform parts are solid and 

 firm : examples are bone, fish-spine, sinew, blood- 

 vessel. This division of the uniform parts admits a 

 further distinction : There are some of them of which 

 a portion has, in one sense, the same name as the 

 whole (e.g. a portion of a blood-vessel has the name 

 blood-vessel), and in another sense has not the 

 same name. (In no sense is this the case with a 

 non-uniform part ; for instance, a portion of a face 

 cannot be called face at all.) 



117 



