MONSTERS IN ANIMALS. 245 



Of Monstrosities after Birth. 



These occur only in certain classes of animals, and in particular parts 

 of these classes. Under what circumstances are these parts different 

 from other parts of the same animal ? Or, in what do they differ from 

 animals in general ? Or, in what respects are they similar to the vege- 

 table? These parts are such as, when removed, grow again. This 

 circumstance makes them different from every other part of the same 

 a n imal, and also from every other already formed animal ; and in this 

 respect they also differ from the vegetable*. 



It is this property of new growth in these parts that gives them a 

 capability to form monsters in these parts, which they readily do : thus 

 we see in a lizard, which, having lost its tail, has the power of gene- 

 rating a new one, that in such we often find a double tail, arising from 

 the broken part 1 ; similar to two or more branches arising from the edge 

 of the cut surface of a branch removed [from a tree]. Lizards therefore 

 have two or more chances or periods in which they can or may form a 

 monstrous tail ; for they have the first formation common to all animals, 

 which should be called the first growth ; and they have the accidental 

 causes of a new or second growth, all which are due exactly to the same 

 principle, viz. a new formation of a part. This, however, arises from 

 an obstruction to the formation of one tail only ; for, if the part which 

 is to form the tail be slit but a very little into two points, these will 

 form each a tail ; so that an obstruction to the natural disposition 

 becomes the cause of another taking place. I have seen this disposition, 

 so strong in the tail of the lizard, that a wound on the side of the tail 

 has given the disposition for a young supernumerary tail to grow out of 

 the wound f 2 . 



This sort of monstrosity does not take place in all the parts of animals 



* It may be remarked that there is a difference in the setting out of the young 

 shoot. In the vegetable it is from the circumference, or from the new forming parts ; 

 but in the animal it is from the cut end. This cut or broken end is exactly similar 

 to a bud which is elongating, 



t It may be remarked that in those lizards that have the power of regenerating 

 the tail, the tail is so constructed as to admit of a regular breaking off. The tail is 

 in regular rings, and readily breaks off at each ring, and the muscles break off at 

 their origins and insertions, so that the broken end is very regular 3 . The separation 

 is so easily effected, that if a lizard be caught by the tail, it will leave it in your hand 

 by the strength of the animal only. 



1 [Hunt. Preps. Phys. Series, Nos. 2219-3223.] 

 - [Hunt. Prep. ib. No. 2219.] 

 3 [Ib. No. 2212.] 



