128 THE MECHANICAL FUNCTIONS. 



resorted to on all occasions where considerable 

 mechanical force is wanted ; just as in a great 

 manufactory, where an immense quantity of 

 machinery is to be set in motion, and a great 

 variety of work is to be executed, the human 

 mechanist avails himself of some constant 

 moving force, such as that of water, or steam. 

 The laws of inorganic matter furnish no pov> er 

 that could conveniently have been applied in 

 the animal body for that purpose ; but muscular 

 power, from its high intensity, is adequate to 

 every object, and has been accurately ad- 

 justed, by the most refined application of the 

 laws of mechanism, to all the degrees and kinds 

 of effects intended to be produced. 



Although the power be the same, yet the 

 mode of its application is exceedingly diversi- 

 fied ; and the comparison of these diversities , 

 is the more interesting, inasmuch as there are 

 few of the animal functions in which the ends 

 to be answered are so definite, and the opera- 

 tion of the expedients employed is so plain and 

 intelligible. For while the intricate chemical 



■o' 



leaves of the Dioncea viuscipula; and the shrinking of those 

 of the Mimosa j^udica, or sensitive plant. On a superficial 

 view, it must be acknowledged that these motions bear a re- 

 semblance to the effects of muscular contractility ; but I believe 

 that naturalists are now generally agreed that there is no real 

 analogy between these phenomena, and that there is no sub- 

 stantial evidence for the existence of that property in the vege- 

 table kingdom. 



