112 ANIMALSENTIENT FORCES. [i. 



is perceived, the muscular pupil of the eye undergoes a change. 

 The light has no more such effect upon the pupil of the 

 blind than in a corpse, consequently it is a true direct sentient 

 action from an external sensation. When a savoury drop 

 or two is tasted posteriorly, by means of the tongue, the 

 throat is stimulated to the act of swallowing ; and when the 

 skin is affected by an acute external sensation, as from cold or 

 itching, it is contracted, and its exhalation altered (177). 

 These are obviously sentient actions in the organs of the senses 

 from external sensations, rendering them more fit for their 

 functions, and testifying to a fore-seeing wisdom. 



217. All that need be said as to the direct sentient actions 

 of external sensations in the sexual organs has been already 

 stated ; it is their great characteristic that they render the 

 organs fit for the function of reproduction. 



218. We may now estimate from previous considerations 

 (204 — 207) the law laid down by Kriiger, in his ' Physiology,' 

 that every external sensation is followed by a movement in the 

 body proportionate to the sensation. In the ordinary state of 

 the body, whenever an external sensation is excited in the mind 

 through a nerve which is distributed to mechanical machines, 

 such movements are developed in the machines by means of the 

 nerve, its branches and fibrils, provided there are no natural 

 hinderances there (136, 199), as in virtue of their structure they 

 are capable of, and the movements are the stronger in propor- 

 tion as the external sensation is more vivid (194). But it may so 

 occur (as will be demonstrated in another part of this work,) 

 that the same movements may result from an external im- 

 pression which is not felt, and thus be nerve-actions (83, 462). 

 This law is, however, not to be understood, to the effect that 

 the movements will be stronger in proportion as the external 

 contact on the nerve is stronger, or according to the measure 

 of physical forces, but the stronger the external impression is, 

 which may sometimes be very strong from a slight contact, and 

 vice versa (40). 



219. Besides the direct sentient actions of external sensations 

 that we have hitherto considered (204 — 218), we have also to 

 consider the incidental^ [zufallig] which are so often confounded 

 with the former. It may be stated generally, that the sentient 

 actions of both kinds, and all the mental forces possessed 



