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



perhaps fometimes for the purpofe of diffufmg a-pirt of it over 

 _ihe dry membranes of the fauces and pharynx ; in the fam-3 

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

 act of nictitation to clean or moiften it. 



3. Refpiratio et TuJJis irritative. In the ats of refpiration 

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

 the lungs owing to Come ftimulating caufe, as delcribed above 

 in Clafs I. i. 2. 8. and I. I. 3. 4. and which are frequently per- 

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

 ritative actions j and thus differ from thofe defcribed in Clais II. 

 i. i. 2. and 5. To thefe increafed actions of the air-cells are 

 fuperadded thofe of the intercoital mufcies and diaphragm by 

 irritative aflbciation. When any unnatural ftimulus 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 confequence. 



4. Excltifto bills. The exclusion of the bile from the gall-blad- 

 der, and its derivation into the duodenum, is an irritative ad ion 

 in confequence of the ftimulus of the aliment on the extremity 

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

 creafed fecretion of tears is occafioned in a limilar manner by 

 any ftimulating material in the eyes ; which afFetts the excretory 

 duels of the lachrymal glands. A pain of the external membrane 

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

 fenforial power of fenfatioa becomes added to that of irritation, 

 and a fuperficial inflammation is induced. 



5. Dentitis. Toothing. The pain of toothing often begins 

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

 fions , which are fometimes relieved, when the gum fwells, and 

 becomes inflamed ; at other times a diarrhoea fupervenes, which 

 is generally efteemed a favourable circumitance, and feems to 

 prevent the convulsions by fupplying another means of relieving 

 the pain of dentition by irritative exertion ; and a confequent 

 temporary exhaustion of fenforial power. See Clafs I. 1.2. c. 

 Sea. XXXV. 2. i. 



The convulfions from toothing generally commence long be- 

 fore the appearance of the teeth ; but as the two middle incii*- 

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

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

 nally in refpecl: to the jaw-bones, and quite down to the perios- 

 teum, and through it. 



As the convulfions attendingthe commencement of toothing are 

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

 induce ftupor or infenfibility by their continuance even in a lefs 

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



Vol. II. G IVL M. Lance 



