Class I. i. 4. 3. OF IRRITATION. 41 



perhaps fometimes for the purpofe of diffufing a part of it over 

 the dry membranes of the fauces and pharynx ; in the fame 

 manner as tears are diffufed over the cornea of the eye by the 

 act of nictitation to clean or moiftcn it. 



3. Rejpirr.tio ei TuJJts itritativte. In the acts of refpiration 

 and of coughing there is an increased motion of the air-cells of 

 the lungs owing to fome ftimulating caufe, as defcribed above 

 in Oafs I. 1. 2. 3. and I. 1. 3. 4. and which are frequently per- 

 formed without our attention or confcioufnefs, and are then ir- 

 ritative actions ; and thus differ from thofe defcribed in Clafs IT« 

 1. 1.2. and 5. To thefe increafed actions of the air-cells are 

 fuperadded thofe of the intercoftal mufcies and diaphragm by 

 irritative affociation. When any unnatural fcimulus acts fo vi- 

 olently on the organs of refpiration as to induce pain, the fenfo- 

 rial power of fenfation becomes added to that of irritation, and 

 inflammation of the membranes of them is a general conicquence. 



4. Exclufw bilis. The exclufion of the bile from the gall-blad- 

 der, and its derivation into the duodenum, is an irritative action 

 in confequence of the ffcimulus of the aliment on the extremity 

 of the biliary duct, which terminates in the inteftine. The in- 

 creafed fecretion of tears is occafioned in a fimilar manner by 

 any ftimulating material in the eyes 5 which affects the excretory 

 ducts of the lachrymal gia^'.s. A pain of the external membrane 

 of the eye fometimes attends any unufual fcimulus of it, then the 

 fenforial power of fenfation becomes added to that of irritation, 

 and a fuperficial inflammation is induced. 



5. Dentit'iQ. Toothing. The pain of toothing often begins 

 much earlier than is fufpected ; and is liable to produce convul- 

 fions *, which are fometimes relieved, when the gum fv/ells, and 

 becomes inflamed ; at other times a diarrhoea fupervenes, which 

 is generally efleemed a favourable circumftance, and ieerns to 

 prevent the convulfions by fuppiying another means of relieving 

 the pain of dentition by irritative exertion ; and a confequeiu 

 temporary exhauition of fenforial power'. Gee Ciafs 1. 1. 2. 5- 

 Sect. XXXV. 2. 1. 



The convulfions from toothing generally commence long be- 

 fore the appearance of the teeth ; but as the two middle incif- 

 ors of the lower jaw generally appear nrft, and then thofe of 

 the upper, it is advifable to lance the gums over thefe longitudi- 

 nally in refpect to the jaw-bones, and quite down to the periof- 

 teum, and through it. 



As the convulfions attendingthe commencement of toothing are 

 not only dangerous to life in their greardl degree, but are liable to 

 induce itup^r or infenfibliity by their continuance even in a lefs 

 degree, the mod efficacious means ihould be ufed to cure them. 



Vol. IL G M. M. Lance 



