PHYSIOLOGY. 157 



but if the stimulus was not determined to produce the pro- 

 pensity of vomiting, this would not follow ; so it may take 

 place in consequence perhaps of an application of that stimulus 

 to any one nerve of the system. 



" I do maintain that you will find no other explanation of what 

 may be strictly called sympathy and consent, but the accessary 

 concurrence of certain actions to a volition or propensity, and 

 the concurrence of several motions of the system produced in 

 consequence of these volitions and propensities. Whether the 

 connexion between the nerves of the teeth and those of the 

 ear (see p. 44.), is an exception to what we have here said 

 of lateral communications, I do not positively say. There is a 

 communication between parts whose membranes are conti- 

 guous, such as the neck of the bladder and orifice of the urethra, 

 between the intestines and abdominal muscles, the ear and 

 glottis ; but there the vicinity of parts is to be taken into ac- 

 count. You will, I think, be able to distribute such instances 

 in the manner I have pointed out, and be relieved from much 

 confusion and appearance of mystery, which this language of 

 sympathy has introduced into our system of physic." 



CXLV. These are the chief facts and laws relative to the 

 nervous system. The whole might perhaps be illustrated, and 

 more exactly ascertained by a more particular inquiry into the 

 nature of the nervous fluid ; but we are not so confident in our 

 opinion on this subject, nor of the application it will admit of, 

 as to deliver it here. " I do not say that this is the theory of 

 the nervous system ; I say that these are the facts and laws ; 

 and wherever, in some instances, you may think I have ap- 

 proached to theory, I would wish you to receive every parti- 

 cular I have delivered with great diffidence, till you are per- 

 suaded that the conclusion is established as a matter of, fact. 

 If you do so, there will be no danger of misapplication ; you 

 will be constantly enlarging the number of facts, and be much 

 more fit for the application of them. 11 



