272 ANIMAL FORCES. [ii. 



528. The functions of glandular structures generally must 

 be comprised in the same proposition, except in those cases in 

 "which secretion or excretion is effected by means of muscular A 

 tubes, or the action of adjoining muscles (172). Since secretion 



is effected by the action of stimuli on the mouths of the capil- 

 laries, the general views already stated are applicable to it. 

 Thus, by means of the vis nervosa of non-conceptional internal 

 impressions, certain external impressions of food and poisons in 

 the stomach which are not felt, excite a flow of saliva and a 

 discharge from the bronchial tubes, as an indirect nerve- 

 action (419). 



529. The glands, whose functions are regulated by muscular 

 action, are subject to laws previously stated (172, 473). 



530. Although the glandular system is excited to the per- 

 formance of its functions by cerebral forces (172, 209), as well 

 as by the vis nervosa, yet the latter is the most general and 

 most usual excitant. Many glandular functions go on in de- 

 capitated animals, so long as they possess vis nervosa and the 

 functions are not interrupted by deep sleep, syncope, &c. They 

 are observed, too, in many animals not endowed by nature 

 with cerebral forces. 



531. The oesophagus, stomach, and intestinal canal, are 

 capable of nerve-actions from non-conceptional internal im- 

 pressions. Vomiting, from injury of the brain, is an illustrative 

 example (490) ; colic or diarrhoea, produced by the application 

 of poisons externally to the umbilical region, is another ; ver- 

 micular action excited by puncture of a portion of the intestinal 

 canal, another (513). 



532. Although the movement of the digestive apparatus is 

 usually a direct nerve action of external impressions, and con- 

 sequently requires neither the cerebral forces, nor the concep- 

 tive force (466, 467), nevertheless, not only conceptional internal 

 impressions often change it (170, 174, 206, 212), but it also 

 requires the co-operation of non-conceptional internal impres- 

 sions for its continuance, just as is required in the movements 

 of the heart, diaphragm, and other parts; for the moving 

 power of the stomach is abolished, when the trunk of its 

 nerves is tied. Hence the continued connection of its nerves 

 with the brain is necessary to the movement of the digestive 

 apparatus, although independent of the cerebral forces and 



