INTRODUCTION. 25 



it from the blood, testes; and when it is requisite it should be 

 carried into the body of the female, the introductory organ is 

 named a penis. 



Of the Intellectual Functions of Animals. 



The impression of external objects upon the me, the produc- 

 tion of a sensation or of an image, is a mystery into which the 

 human understanding cannot penetrate ; and materialism an 

 hypothesis, so much the more conjectual, as philosophy can 

 furnish no direct proof of the actual existence of matter. The 

 naturalist, however, should examine what appear to be the 

 material conditions of sensation, trace the ulterior operations 

 of the mind, ascertain to what point they reach in each being, 

 and assure himself whether they are not subject to conditions 

 of perfection, dependent on the organization of each species, 

 or on the momentary state of each individual body. 



To enable the me to perceive, there must be an uninter- 

 rupted communication between the external sense and the 

 central masses of the medullary system. It is then the modi- 

 jfication only experienced by these masses that the me per- 

 ceives : there may also be real sensations, without the exter- 

 nal organ being affected, and which originate either in the 

 nervous chain of communication, or in the central mass itself; 

 such are dreams and visions, or certain accidental sensations. 



By central masses, we mean a part of the nervous system, 

 that is so much the more circumscribed, as the animal is more 

 perfect. In man, it consists exclusively of a limited portion 

 of the brain j but in reptiles, it includes the brain and the 

 whole of the medulla, and of each of their parts taken sepa- 

 rately, so that the absence of the entire brain does not pre- 

 vent sensation. In the inferior classes this extension is still 

 greater. 



The perception acquired by the me, produces the image of 

 the sensation experienced. We trace to without the cause of 

 that sensation, and thus acquire the idea of the object that has 

 produced it. By a necessary law of our intelligence, all ideas 

 of material objects are in time and space. 

 Vol. I. D 



