396 



THE MECHANICAL FUNCTIONS. 



complication at least, although on a microscopic scale, an 

 extensive manufactory. Hence will be readily understood 

 how great must be the difficulty of tracing all the steps of 

 these multifarious processes, which are carried on in so 

 small a space: and this difficulty is much increased from the 

 circumstance that the organ in which they take place is it- 

 self only developed as the work proceeds, its different parts 

 being produced successively in proportion as they are want- 

 ed, and their form and structure undergoing frequent varia- 

 tion in the course of their development. 



230 231 



228 .- 229 



i-!'!"il)llllK H A 



S-^- 



nriiiii!. 



The most elaborate and apparently accurate researches on 

 this intricate subject, are those lately undertaken by M. 

 Frederick Cuvier, from whose memoir* I have selected 

 the following abridged statement of the principal results of 

 his observations. It will be necessary, in order to obtain a 



* M^moires du Museum, xiii. 327; and Annales des Sciences Nuturelles, 

 ix. 113. 



