o 



304 DISEASES CLASS III. r. 2, 



There is finally reafon to believe, that not only fenforial power 

 in general is capable of accumulation in thofe parts which 

 have been accuftomed to almoft perpetual action ; but alfo that 

 each kind or fpecies of fenforial power, as that of irritation, 

 fenfation, volition, and alTociation, is feparately capable of accu- 

 mulation in the parts, which have almoft perpetually been actu- 

 ated by it : which I hope fometime to confider more at large, as 

 I fufpecT: it may fupply a key to many of the phenomena not 

 only of infanities and convulfions, but to thofe of fever. 



The difpofition to infanity, as well as to convulfion, is believ- 

 ed to be hereditary ; and in confequence to be induced in thofe 

 families from /lighter caufes than in others. Convulfions have 

 been (hewn to have besn moft frequently induced by pains ow- 

 ing to defecl: of ftimulus, as the (huddering from cold, and not 

 from pains from excefs of ftimulus, which are generally fucceed- 

 ed by inflammation. But mfanities are on the contrary gener- 

 ally induced by pains from excefs of ftimulus, as from the too 

 violent actions of our ideas, as in common anger, which is an 

 infanity of (hort duration ; for infanities generally, though not 

 always, arife from pains of the organs of fenfe ; but convulfions 

 generally, though not always, from pains of the membranes or 

 glands. And it has been previoufly explained, that though the 

 membranes and glands, as the ftomach and Ikin, receive great 

 pain from want of ftimulus ; yet that the organs. of fenfe, as the 

 eye and ear, receive no pain from defeft of ftimulus. 



Hence it follows, that the conftitutions moft liable to convul- 

 fion, are thofe which moft readily become torpid in fome part 

 of the fyftem, that is which poiTefs lefs irritability ; and that 

 thofe moft liable to infanity, are fuch as have excefs of fenfibil- 

 ity ; and laftly, that thefe two circumftances generally exift in 

 the fame conftitutioii ; as explained in Seel. XXXI. 2. on Tern* 

 perajnents. Thefe obfervations explain why epilepfy and infan- 

 ity frequently fucceed or reciprocate with each other, and why 

 inirritable habits, as fcrofulous ones, are liable to infanity, of 

 which I have known fome inftances. 



In many cafes however there i$ no appearance of the difpofi- 

 tion to epilepfy or infanity of the parent being tranfmitted to 

 progeny. Firft, where the infanity has arifenfrom fome vi- 

 lent difappointment, and not from intemperance in the ufe of 

 fpirituous liquors. Secondly, where the parent has acquired the 

 infanity or epilepfy by habits of intoxifcation after the procrea- 

 tion of his children. Which habits I fuppofe to be the general 

 e of the difpofition to infanity in this country. See Clafs 

 til. i. i. 7. 



As the difpofition to gout, dropfy, epilepfy, and infanity, ap- 



pears 



