so THE MECHANICAL FUNCTIONS. 



must require a union of strength and flexibility in the parts 

 intended for extensive motion, and for being acted upon by 

 poweiful moving forces. 



The animal, as well as the vegetable fabric is necessarily 

 composed of a union of solid and fluid parts. Every animal 

 texture appears to be formed from matter that was original- 

 ly in a fluid state: the particles of which they are composed 

 having been brought together and afterwards concreting by 

 a process, which may, by a metaphor borrowed from physi- 

 cal science, be termed animal crystallization. Many of those 

 animals, indeed, which occupy the lowest rank in the se- 

 ries, such as Medusae, approach nearly to the fluid state; ap- 

 pearing like a soft and transparent jelly, which by spontane- 

 ous decomposition after death, or by the application of heat, 

 is resolved almost wholly into a limpid watery fluid.* More 

 accurate examination, however, w^ill show that it is in reali- 

 ty not homogeneous, but that it consists of a large propor- 

 tion of water, retained in a kind of spongy texture, the indi- 

 vidual fibres of which, from their extreme fineness and 

 uniformity of distribution, can with difliculty be detected. 

 Thus, even those animal fabrics which on a superficial view 

 appear most simple, are in reality formed by an extremely 

 artificial and complex arrangement of parts. The progress 

 of development is continually tending to solidify the struc- 

 ture of the body. In this respect the lower orders of the 

 animal kingdom, even when arrived at maturity, resemble 

 the conditions of the higher classes at the earliest stages of 

 their existence. As we rise in the scale of animals, we ap- 

 proximate to the condition of the more advanced states of 

 development which are exhibited in the highest class. 



Great efibrts have been made by physiologists to discover 

 the particular structure which might be considered as the 

 simplest element of all the animal textures; the raw mate- 

 rial, as it were, with which the whole fabric is wrought: 



* Thus a Medusa, weighing- twenty or thirty pounds, will, by this sort of 

 general liquefaction, be found reduced to only a few grains of solid matter. 

 Peron, Annales du Musee, torn. XV. p. 43. See also a memoir by Quoy and 

 Gaimardf Annales des Sciences Naturelles, torn. I. p. 245. 



