INTRODUCTION. 9 
Division of Organized Beings into Animals and Vegetables. 
Living or organized beings have always been subdivided into animate 
beings, that is, such as are possessed of sense and motion; and into inani- 
mate beings, which are deprived of both these faculties, and are reduced 
to the simple faculty of vegetating. Although the leaves of several plants 
shrink from the touch, and the roots are steadily directed towards mois- 
ture, the leaves to light and air, and though parts of vegetables appear to 
oscillate without any apparent external cause, still these various motions 
have too little similarity to those of animals, to enable us to find in them 
any proofs of perception or will. 
The spontaneity in the motions of animals required essential modifications 
even in their purely vegetative organs. Their roots not penetrating the 
earth, it was necessary they should be able to place within themselves a 
supply of aliment, and to carry its reservoir along with them. Hence is 
derived the first character of animals, or their alimentary canal, from which 
their nutritive fluid penetrates all other parts through pores or vessels, 
which are a kind of internal roots. 
The organization of this cavity and its appurtenances required varying, 
according to the nature of the aliment, and the operation it had to under- 
go, before it could furnish juices fit for absorption; whilst the air and 
earth present to vegetables nought but elaborated juices ready for ab- 
sorption. 
The animal, whose functions are more numerous and varied than those 
of the plant, consequently necessitated an organization much more com- 
plete; besides this, its parts not being capable of preserving one fixed re- 
lative position, there were no means by which external causes could pro- 
duce the motion of their fluids, which required an exemption from atmos- 
pheric influence; from this originates the second character of animals— 
their circulating system, one less essential than that of digestion, since in 
the more simple animals it is unnecessary. The animal functions required 
organic systems not needed by vegetables—that of the muscles for volun- 
tary motion, and nerves for sensibility; and these two systems, like the 
rest, acting only through the motions and transformations of the fluids, it 
was necessary that these should be most numerous in animals, and that the 
chemical composition of the animal body be more complex than that of the 
plant; and so it is, for one substance more (azote) enters into it as an es- 
sential element, whilst in plants it is a mere accidental junction with the 
three other general elements of organization—oxygen, hydrogen, and car- 
bon. ‘This then is the third character of animals. 
From the sun and atmosphere, vegetables receive for their nutrition, 
water, which is composed of oxygen and hydrogen; air, which contains 
