GREEK BIOLOGY AND MEDICINE 



tion of every animal and every part of an 

 animal, since everything that nature makes is 

 a means to an end, and nature does nothing 

 in vain. " It is evident that there must be 

 something or other really existing, correspond- 

 ing to what we call by the name of Nature. 

 For a given germ does not give rise to any 

 chance living being, nor spring from any 

 chance one; but each germ springs from a 

 definite parent and gives rise to a definite 

 progeny. And thus it is the germ that is the 

 ruling influence and fabricator of the off- 

 spring." ^° 



The classification of living beings should 

 take account, it would seem, both of their char- 

 acteristics and of the processes by which they 

 and their characteristics came into existence. 

 In either case nature herself makes no break, 

 admits no gap, in the whole scale of animate 

 and inanimate being: " Nature proceeds little 

 by little from things lifeless to animal life in 

 such a way that it is impossible to determine 

 the exact line of demarcation, nor on which 

 side thereof an intermediate form should be. 

 Thus, next after lifeless things in the upward 

 scale comes the plant, and of plants one will 

 differ from another as to its amount of apparent 



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