16 PRINCIPLES OF PHYSIOLOGY. 



8. The doctrines of animal nature presuppose the doctrine 

 of physical and organic nature (3, 5, 6), and must contan : 



i. A description of the animal machines in the bodies of 

 animals, comprising the composition and structure of their 

 parts, and of their system of relation to each other. 



ii. The determination of the animal forces proper to them 

 alone, and without reference to their influence on the other 

 parts and functions of the organism. 



iii. The determination of their influence on these other 

 organs and functions. 



All primary animal forces are either animal-sentient forces, 

 or nerve-forces (purely animal) (6) ; and hence arises the great 

 divisions of the entire philosophy of animal nature. 



The First Part considers animal nature in its connection with 

 the thinking power of the soul of the animal, and includes : 



i. The animal machines in general, in so far as they are 

 capable of the action of the animal-sentient forces (6). — 

 Part I, Chap. I. 



ii. The animal forces, per se, without reference to their 

 influence on the rest of the mechanism, and considered specially 

 as animal sentient forces (6, 7). — Part I, Chap. II. 



iii. The influence of the animal- sentient forces on the rest of 

 the mechanism of the animal body (6, 7). — Part I, Chap. III. 



iv. The connection of the body and soul generally. — Part I, 

 Chap. IV. 



The Second Part treats of animal nature with reference to its 

 simply animal forces, according to which the animal machines 

 do not act in connection with the sentient faculty of the animal 

 (355). 



Lastly, in the Third Part, animal nature is treated of as a 

 whole (599) : in this Part we consider its essential characte- 

 ristics in the difl'erent kinds of animals, its origin, continuance, 

 and state of perfection ; its entire system of animal forces, its 

 decline, and finally its cessation. 



Man is by no means the only object of this work, although, 

 as the most perfect of animals, he is its principal object ; it 

 contains rather the principles of a Zoology, or natural history 

 of every species of animal, but only according to their peculiar 

 animal forces; and as to these, only in outline (15). 



