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 
Animals, 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 whole body, which 
is traversed in every direction by nerves whose extreme fila- 
ments expand on the surface into papillz, 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 papille 
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 animals have neither ears nor nostrils, several are 
without eyes, and some are reduced to the single sense of 
touch, which is never absent. 
