FOREWORD 



Aristotle refers to the De partibus animaliiim as an 

 inquiry into the causes that in each case have deter- 

 mined the composition of animals. He does not, 

 hoΛvever, employ the category of causation in the 

 manner normally adopted by men of science, since 

 in this book causes are ahvays considered in relation 

 to ends or purposes, and design is regarded as having 

 had a far larger share in the origin and development 

 of living structures than that allotted to necessity. 



In the Histor'ia ajiimalium the parts themselves are 

 described, for although this work is to some extent 

 physiological, its main object Λvas to deal with the 

 anatomy of the organism. The De partibus ariimaliu?n, 

 on the other hand, is almost exclusively physiological 

 and teleological, and treats of the functions of the 

 parts. But Aristotle's position Avas that of a teleo- 

 logist only in a limited degree, for he appears to 

 have taken that view of life which Bergson calls the 

 doctrine of internal finality (that is to say, that each 

 individual, or at any rate each species, is made for 

 itself, that all its parts conspire for the greatest good 

 of the Λνΐιοίε, and are intelligently organized in view 

 of that end but without regard for other organisms 

 or kinds of organisms). Since every organ or part 

 of the body was held to have its peculiar function, 

 the existence of vestigial or rudimentary organs was 

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