INTRODUCTION. 19 



possibility of accounting for all the phenomena of physical life, 

 from the properties it presents^, by the simple admission of a 

 fluid such as we have defined. 



Summary idea of the Functions and Organs of the Bodies of 

 Animalsy and of their various degrees of Complication. 



After what we have stated respecting the organic elements 

 of the body, its chemical principles and acting powers, no- 

 thing remains but to give a summary idea of the functions of 

 which life is composed, and of their appropriate organs. 



The functions of the animal body are divided into two 

 classes : 



The animal functions, or those proper to animals, that is to 

 say, sensibility and voluntary motion. 



The vital, vegetative functions, or those common to animals 

 and vegetables, i. e., nutrition and generation. 



Sensibility resides in the nervous system. 



The most general external sense is that of touch ; it is seated 

 in the skin, a membrane that envelopes the wlhole body, which 

 is traversed in every direction by nerves whose extreme fila- 

 ments expand on the surface into papillae, and are protected 

 by the epidermis and other insensible teguments, such as hairs, 

 scales, &c. &c. Taste and smell are merely delicate states of 

 the sense of touch, for which the skin of the mouth and nos- 

 trils is particularly organized : the first, by means of papillae 

 more convex and spongy ; the second, by its extreme delicacy 

 and the multiplication of its ever humid surface. We have 

 already spoken of the ear and the eye. The organ of gene- 

 ration is endowed with a sixth sense, seated in its internal 

 skin ; that of the stomach and intestines declares the state of 

 those viscera by peculiar sensations. In fine, sensations more 

 or less painful may originate in every part of the body 

 through accident or disease. 



Many anijiuals have neither ears nor nostrils, several are 

 without eyes, and some are reduced to the single sense of 

 touch, which is never absent. 



