35 



things are connected together, only by palpable and material links; here 

 the chain is invisible, the connexion evident, the cause occult, and the 

 effect apparent. 



Whytt has clearly shown, that the nerves cannot be considered as the 

 exclusive instruments of sympathy*, since several muscles of a limb 

 which receive filaments from the same nerve, do not sympathize together, 

 while there may be a close and manifest relation between two 

 parts, of which the nerves have no immediate connexion, since each ner- 

 vous filament having one of its extremities terminating in the brain, the 

 other, in the part to which it is sent, remains distinct from those of the 

 same trunk, and does not communicate with them. 



Sympathies may be distinguished into different kinds. In the first 

 place, two organs, which execute similar functions; the kidnies may 

 supply each other's office. When the uterus is in a state of pregnancy, 

 the breasts participate inits condition, and there is determined into them 

 a flow of blood necessary to the secretion which is to take place. 

 Secondly. The continuity of membranes is a powerful source of sympa- 

 thy. The presence of worms in the bowels, determines an uneasy itch- 

 ing around the nostrils. When there is a stone in the bladder, a certain 

 degree of itching is felt at the extremity of the glans. The secretion 

 of several fluids is determined in the same manner: thus, the presence of 

 food in the mouth, causes at the extremity of the parotid duct, an irri- 

 tation which extends to the parotid glands, calls them into action, and 

 increases their secretion. Thirdly. If the pituitary membrane is irrita- 

 ted, the diaphragm with which it has no immediate organic connexion, 

 nervous, vascular, or membranous, contracts and occasions sneezing. Is 

 not this sympathy one of those which Haller ascribed to a re-action of 

 the sensorium commune ? If the impression produced on the olfactory 

 nerves by snuff, is too powerful, the uneasy sensation is transmitted to 

 the brain, which determines towards the diaphragm, a quantity of the 

 principle of motion sufficient to enable that muscle suddenly to contract 

 the dimensions of the chest, so as to expel a column of air, that may de- 

 tach from the pituitary membrane, the substances that are a cause of un- 

 easiness to it. Fourthly. Does not the principle of life seem to controul 

 at pleasure the phenomena of sympathy ? The rectum, when irritated by 

 the presence of the excrements, contracts ; what cause determines the ac- 

 cessory and simultaneous action of the diaphragm and abdominal mus- 

 cles ? Does this connexion depend on organic communications ? Why, 

 then, is not the sympathy reciprocal, and why does not the rectum con- 

 tract, when the diaphragm is irritated ? Fifthly. Can the repeated habit 

 of the same motions explain the harmony which is observed in the sym- 

 metrical organs ? Why, when our sight is directed to an object, placed 



* Whytt's opinion must be cautiously received, for the following reason. We know 

 of no mode by which impressions can be communicated, except through the medium of 

 the nerves. It would then, be a much safer conclusion, to state that we are ignorant 

 of the exact manner in which sympathies are affected by the nerves, than to resort to a 

 supposed cause. We do not see any particular necessity that nerves going to several 

 muscles of a limb should cause them uniformly to sympathise. In the bi-ain we find 

 nerves endowed with the most dissimilar powers arising almost from the same point 

 and from the same cerebral substance. For a sketch of some nervous communications 

 and an explanation of certain sympathies, see a paper by John D. Godman^ M. D. in 

 the Philad. Journal of Med. and Phys. Sciences, Vol. VH, p. 237- 



