INTRODUCTION. 25 
it from the blood, éesfess and when it is requisite it should be 
carried into the body of the female, the introductory organ is 
named a pents. 
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- 
fication 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; but in reptiles, it includes the brain and the 
whole of the meduila, and of each of their parts taken sepa- 
_vately, so that the absence of the entire brain does not pre- 
vent sensation. In the inferior elasses this extension 1s still 
greater. 
The perception acquired by the mx, 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 iitelligelte all ideas 
of material objects are in time and space. é 
~  * Vou. I.—D 
