CH. III.] EXTERNAL SENSATIONAL ACTIONS. 107 



observed (160). Although the distinguished Haller wishes to 

 withdraw this proposition once stated by him, he cannot with- 

 stand the force of facts, and observes : '^ Aliquid autem in 

 luinimis vasis esse, quod laqueorum nerveorum similitudiuem 

 certe in effectu habeat, adparet ex suppress© sanguinis venosi 

 motu in pene, analogo effectui vinculorum, et ex tuberculis 

 cutaneis, quse perinde a terrore ut ex frigore nascuntur.'^ 

 (Element. Physiol.,, torn, v, p. 590.) 



206. External sensations also cause contraction of the mus- 

 cular tubes, as the oesophagus and intestines, whereby their 

 natural function — the transmission of the food (170) — is fur- 

 thered. Pain causes a spasm in these organs which hinders 

 their natural functions (204). 



207. All observation shows, that every external impression 

 at the mouths of the capillary vessels, whether they contain 

 blood or other fluids, which is felt (and also an impression 

 which is not felt, as will be proved in the Second Part), 

 attracts their fluid contents to their mouths, where the fluid 

 either accumulates, or is effused. " Dolori multa fere cum 

 voluptate communia sunt ; fortior nempe sensus, fortior etiam 

 sanguinis confluxus ad eam partem, quse vel voluptate emovetur 

 vel dolore; exempla sunt in venereis organis, in ipsis oculis 

 acrius tuentibus, in fricta cute.^^ (Haller, ' Elem. Physiol.,' 

 tom. V, p. 597.) This action is animal, for it is not a property 

 of other mechanical machines, although they also possess similar 

 canals ; nor is it observed in dead animals ; and, consequently, 

 does not result from mere mechanism (7) ; and so far as it usually 

 follows in the same parts on external sensation, it is a direct sen- 

 tient action from external sensation (98, 186). The direct action 

 of external sensations on the blood-vessels, is a contraction (205). 

 When the terminations of the arterial capillaries, which are either 

 continuous with the venous radicles, or open into cavities, become 

 contracted, the continually flowing stream accumulates in them, 

 and they are stretched and dilated, and thus, according to the 

 mechanical principles of pathology, congestion, swelling, and in- 

 flammation arise. It is in this way that those arteries are ex- 

 cited to pulsation by the pain of inflammation, in which it usually 

 does not occur. (Haller^s ' Physiology,' § 33.) If the capillaries 

 open into shut sacs, the great distension of their mouths dilates 

 the opening, and then copious effusion of the congested fluids 



