456 BIOLOGY. 



tern. Taken in a strict sense, there are no vegetative 

 organs. The organs are therefore limited to the encephalic 

 animal, such as are those of motion and the senses, and 

 to the sexual animal. 



1. Functions of the Encephalic Animal. 



A. ORGANS OF MOTION. 



2770. Just as the nerves have a function in them- 

 selves, and one directed towards the subordinate organs, 

 so also has the motor system. 



2771. The motor system is in the first place doomed 

 to serve the whole body, since it flexes it, moves it for- 

 wards and backwards and upon all sides. It is related 

 principally to the movements of the vertebral column, and 

 serves in numberless animals to effect the act of crawling 

 or creeping. 



2772. Then again it will serve individual parts of 

 the body, such as the belly in its evacuations, or the 

 sexual animal in emitting urine, &c. It ministers unto 

 the thorax in the act of respiration, which is a very com- 

 plicated process. The thoracic muscles are to a certain 

 degree co-ordinated with the constantly polar nervous 

 system, and become thereby and in part involuntary. 

 But one main reason of this appears to be the air that is 

 constantly renewed in their cavity. 



2773. In the act of respiration two orders of muscles 

 are active, the proper-pectoral muscles, and the abdo- 

 minal muscle, which has been displaced from the thorax, 

 or the diaphragm. 



2774. As originally the thorax took its rise at the 

 expense of the abdomen, so also is every inspiration an 

 elevation of the thorax and a displacement of the abdo- 

 men. Every breath or in-draught of air expands and 

 produces the thorax, but narrows and arrests the abdo- 

 men. The diaphragm expresses this contest. Its con- 

 traction being a result of the respiratory tension, expres- 

 ses consequently a preponderance of the thorax, and in 

 obedience to this, narrows and diminishes the abdomen. 



