38 PHILOSOPHY OF ZOOLOGY. 



are not connected with the skeleton, but produced by the 

 skin, and differ in nothing but shape from the nails of the 

 fingers or toes. Where such excrescences have been ob- 

 served on sheep, they have resembled the substance of the 

 hoof*. 



In all these different instances of monstrosity, in the Ani- 

 mal Kingdom, (and many similar cases might have been 

 enumerated,) in which certain organs perform functions 

 which are unnatural to them, we still find limits assigned 

 even to these aberrations. The new parts, how extraordi- 

 nary soever they may appear, are still similar to the parts 

 of some other portion of the system. The organs which 

 characterise one species, are never produced on other spe- 

 cies as monstrosities ; so that there is no mixture or trans- 

 mutation. The functions of a system may thus be deran- 

 ged, and the harmony of its parts destroyed ; but to such ir- 

 regularities there are bounds which are never exceeded (. 



These occurrences, which take place during the conti- 

 nuance of life, serve greatly to r shorten its duration. Neither 

 dwarfs nor giants survive the usual period of existence. The 

 attainment of the senile tvd&vao-ut, so anxiously wished for 

 by all, only takes place when there is an equilibrium be- 

 tween all the organs ; when each organ exercises its own 

 peculiar actions ; and when the body escapes the destruc- 

 tive influence of external accidents. Previous to the disso- 

 lution of the fabric, we witness a rigidity of the vessels ; a 

 deficiency of the fluids ; and a cessation of motion. The 

 vital principle then deserts the body which it has construct- 



* Sec Sir EVKRARD HOME'S "Observations on Horny Excrescences of the 

 Human Body." Phil. Trans. 1791, vol. Ixxxi. p. 95.-105. 



f The reader will find some short but pertinent remarks on this sub- 

 ject, by Dr BARCLAY, " On the Causes of Organization." Memoirs of the 

 Wernerian Natural History Society, vol. ii. part. 2. p. 53T.-546. 



