INTRODUCTION. 17 



It is this form which determines the particular 

 direction of every partial movement within it, and 

 regulates the complex operation of the vital action 

 at large*, and it is this form which constitutes the 

 species, and makes it what it is. All the parts co- 

 operate to produce the general movement, by a 

 particular action proper to each, and each in its 



* Although we may grant that the organization and form of a 

 part determine, in some measure, the nature and extent of its func- 

 tions, we may, with equal justice, add that they are merelv the 

 instruments or apparatus, whose operations are much more com- 

 pletely influenced by a principle to which this apparatus is sub- 

 jected, and by which it is entirely actuated : which apparatus, 

 moreover, is itself formed from the circulating fluid, by means of 

 the influence this principle exerts upon the material elements with 

 which it is allied. To the influence of such a principle the or- 

 ganized apparatus is subjected as long as it continues to perform its 

 functions, and as soon as this influence is removed all its opera- 

 tions immediately cease. Thus we perceive that an organ, or part 

 of one of the more perfect of the class of reptiles, may be removed 

 and a similar organ or part be soon afterwards reproduced from the 

 blood, by means of the vessels on the surface whence it was sepa- 

 rated ; and according as this organ becomes more perfectly rege- 

 nerated, so it performs, in a more perfect manner, similar offices in 

 the economy of the animal to those which its predecessor fulfilled. 

 In this case two circumstances excite our attention, viz., the repro- 

 duction of the part, and the perfect performance of its functions 

 when reproduced : 1st, we have no means of explaining — for our 

 acquaintance with the mutual action of the elements or aggregates 

 of matter furnishes us not with the means of explanation derived 

 from that source alone— the regeneration of the part, and the exact 

 form which it assumes, unless we admit that the production of a 

 part or organ is directed by means of a superior and controlling 

 principle in alliance with material elements ; and 2dly, the subse- 

 quent functions of the reproduced organ cannot be otherwise ac- 

 counted for than by assuming that, as it is reproduced, so it be- 

 comes endowed with this principle which afterwards continues to 

 actuate it as long as its operations continue. 

 Vol. I. C 



