PARTS OF ANIMALS 



(a) some of the uniform are the material out of 

 which the non-uniform are made (i.e. each 

 instrumental part is made out of bones, sinews, 

 flesh, etc.) ; 



(6) some act as the nutriment of (a) ; 



(c) some are the residue of (6) — faeces, urine. 



It is not possible to equate the two classes with the 

 later division into tissues and organs, since blood, 

 for instance, though " uniform," is not a tissue ; the 

 term " organs," however, corresponds closely with 

 Aristotle's own description — to. opyaviKa fxcprj 

 (647 b 23), " instrumental parts." 



The practical difference between the two classes 

 is that each of the uniform parts has its o^vn definite 

 character as a substance (in the modern sense), while 

 each of the non-uniform parts has its own definite 

 character as a conformation or organ. The heart is 

 the only part which belongs to both classes (647 a 25 

 foil.) : it consists of one uniform part only, namely, 

 flesh ; but it also has essentially a definite configura- 

 tion, and thus it is a non-uniform part. 



Three stages or " degrees of composition," so far 

 as biology is concerned, are enumerated by Aristotle 

 (at 646 a 13 foil.). What Aristotle seems to mean, 

 though he has not expressed himself quite clearly, 

 is that there are three stages involved in the com- 

 position of compound bodies, namely, 



(1) the 8vvdfi€Ls (see following note) ; 



(2) the uniform parts ; 



(3) the non-uniform parts ; 



and finally, of course, out of the non-uniform parts 



(4) the animal itself is composed. 



