GENERATION OF ANIMALS, IV. iv. 



prolific — in Egypt, for instance." Monstrosities occur 

 more frequently in goats and sheep, because they 

 are more prolific ; and still more frequently in the 

 fissipede animals, because animals of this sort are 

 prolific and the offspring is not perfected when born 

 (e.g., the dog) — most of these creatures' young, of 

 course, are born blind. The cause why this occurs '' 

 and the cause why they are prolific '^ must be stated 

 later. But the way to the production of monstrosities 

 has been already prepared for Nature by the fact that 

 they generate offspring which, owing to its imperfect 

 state, is unlike its parents : — for monstrosities come 

 under the class of offspring which is unUke its parents. 

 And that is why this particular accident extends its 

 range to affect animals of that nature,** and, to bear 

 this out, it is among these animals especially that 

 metachoira ^ as they are called occur. These meia- 

 choira are creatures which have in some respect 

 undergone some " monstrous " affection, since the 

 lack of any part or the presence of an extra part is 

 such an affection. A monstrosity, of course, belongs 

 to the class of" things contrary to Nature," although 

 it is contrarv- not to Nature ki her entirety but only 

 to Nature in the generality of cases.^ So far as con- 

 cerns the Nature which is abrays ' and is hy necessity, 

 nothing occurs contrary to that ; no ; unnatural 

 occurrences are found only among those things which 

 occur as thev do in the generality of cases, but which 

 may occur otherwise. Why, even in those instances 

 of the phenomena we are considering, what occurs 

 is contrary to this particular order, certainly, but 

 it never happens in a merely random fashion ; and 

 therefore it seems less of a monstrosity because 

 even that which is contrary to Nature is, in a 



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