cii. v.] SYSTEM OF THE FORCES OF ANIMAL LIFE. 349 



hypochondria; inflammation of the diaphragm induces fatal 

 delirium and nervous attacks, &o. 



689. There are many other subordinations, but it is not 

 possible to give all in detail in this general sketch ; it is easy, 

 however, to deduce them from the general principles laid down. 



690. The natural subordination of all animal forces we have 

 considered hitherto, has been considered with reference, it is 

 true, to the most perfect type of animal organisation; but, 

 nevertheless, it is applicable to every species of animal, whether 

 sentient or insentient, provided only that they have some of 

 the organs belonging thereto ; for, in the Second Part of this 

 work it has been shown, that the animal functions in question 

 may be performed as well by the vis nervosa only, as by the 

 animal-sentient forces; or by both acting conjointly. But in 

 sentient animals, the brain is a special organ and centre of the 

 animal sentient forces, and of this we have now to treat. 



691. The brain is not capable of an animal -sentient force, 

 without vital spirits (21, 22). Further, its animal-sentient 

 forces are subordinate to the primary vital forces, as regards the 

 secretion of the vital spirits. The proper animal-sentient forces 

 of the brain are the material ideas of conceptions (25), which 

 are always induced primarily by means of external impressions 

 (65), although some of them, namely those of intellectual con- 

 ceptions, desires, &c. are impressed on the brain by the mind, 

 without their being more immediately dependent on external 

 impressions (579, ii.) 



692. As the animal-sentient forces of the brain depend upon 

 external forces that are felt, and all sentient operations in the 

 system are effected through them (97, 6), it follows that the 

 brain, in so far as it is adapted to them, is the centre of the 

 animal-sentient forces (673) ; although the latter are themselves 

 naturally subordinate to the primary vital forces. 



693. Proper animal life endures so long, as, i. The natural 

 functions of tbe primary vital forces continue, at least in some 

 degree, namely, the secretion of the vital spirits in the brain, 

 and the circulation of the blood (640, 641). ii. So long as the 

 brain is not prevented receiving external impressions, or internal 

 impressions from certain conceptions, iii. So long as external 

 impressions, or sensational or intellectual conceptions, induce 

 material ideas in the brain (663, 664.) 



