244 GENERATION. 



As far as I have seen, supernumerary parts never exceed double the 

 natural number. 



An opinion has been advanced that, where there are supernumerary 

 parts, they have belonged to another or twin ; that the supernumerary 

 part was the only one remaining of one of these twins ; and that it had 

 grown to the other like budding in vegetables, or transplanting in 

 animals. 



But monsters in the bird-class entirely contradict this idea. For, in 

 the cicatricula of the egg there never are formed two chickens ; but, 

 when a twin is produced, it is from two yolks: we have, however, 

 monsters in chickens 1 . Would not the circumstance of a supernumerary 

 part of an animal being at the command of one, rather contradict the 

 idea of its being a part of another animal engrafted on the one pos- 

 sessing it ? 



As the first principle in a foetus is the production of new parts, and 

 as it loses that principle as these parts are formed — afterwards only per- 

 fecting them — we are to study the foetus [in reference to the principle of 

 monstrosity] at as early a stage as possible, and consider how parts 

 may be badly formed, how they may be increased in number, or how 

 they may be diminished. 



A part having the power within itself of elongation, will have the 

 power of varying in that elongation according to circumstances ; there- 

 fore a head not yet formed, but only having a disposition to form, may 

 by some accident be disposed to be formed into two heads, and the 

 same with every part of the body. 



On the other hand, that, or any other part, may lose the disposition 

 to form at all, and [the foetus], therefore, be deficient in such part ; or 

 the disposition in the part for growth may be imperfect, and then there 

 is no knowing what form it may be of, just according to the nature of 

 the imperfection. 



A deficiency and a mal-conformation are much more easily conceived 

 than the formation of an additional part ; for, in the first, it may be 

 owing to a part's dying outright ; and, in the second, it may arise from 

 a part's dying in part, or irregularly, by which means the living parts 

 will shoot out irregularly. 



We have one part dying [as to function] when we come to full 

 maturity [qu. old age], viz. the testicles. Xow if these were to die 

 before birth,. the foetus would be reckoned a monster; therefore, as we 

 can produce monsters with supernumerary parts both before and after 

 birth, we may reckon them as monstrous deficiencies after birth. 



1 [Hunt. Preps. Series of Monsters. Nos. 40-44.] 



