38 MEMOIRS OF 



lively limited part in creation, there are many others which 

 exercise peculiar functions, which not only require organs 

 particularly adapted to them, but induce a modification in 

 the general functions. Of all these peculiar functions, 

 feeling and moving at will are the most remarkable, and 

 most influence the other functions. Independent of the 

 chain which links these two faculties, and the double set of 

 organs which they require, they yet carry with them seve- 

 ral modifications into the functions common to all organized 

 beings, and these modifications more particularly belong to 

 and constitute the nature of animals." 



As one example, among many others which the limits of 

 this volume will not allow me to insert, I shall cite M. Cu- 

 vier's general description of digestion. " Vegetables, which 

 are attached to the ground, absorb the nutritive parts of the 

 fluids which they imbibe by means of their roots. These 

 roots divided to infinity, penetrate into the smallest spaces, 

 and, as it were, seek at a distance for nourishment to the 

 plant to which they belong ; their action is tranquil and 

 continuous, and is only interrupted by a drying-up of the 

 juices in the soil which are necessary to them. Animals, 

 on the contrary, not being fixed, and constantly changing 

 place, must carry with them the provision of juices essential 

 for their nutrition ; therefore they have received a cavity in 

 which their alimentary substances are placed, into the cells 

 of which open the pores, or absorbing vessels, and which, 

 according to the forcible expression of Boerhaave, are true 

 internal roots. The size of this cavity, and its orifices, per- 

 mit several animals to introduce solid substances into it ; 

 these require mechanism to divide them liquids to dissolve 

 them ; and nutrition no longer commences by the imme- 

 diate absorption of substances as they are supplied by the 

 ground and the atmosphere ; it must be preceded by a mul- 

 titude of preparatory operations, the whole of which consti- 

 tute digestion." 



From the second division of this first lecture, which treats 

 of the organs of which animals are composed, I shall select 

 the passage concerning the senses, as most interesting to the 

 general reader. After exposing the nervous system in its 

 different bearings ; after noticing the cellular tissue, the 

 medullary substance, the muscles, the bones, the joints, the 



