CLASS II. i. i. 4- OF SENSATION. 153 



them, into too great action, and might thence injure the fenfe 

 of fmell which is diffufed on it. 



In this operation the too great action of the veffds of the 

 membrane of the noilrils is the remote caute , the feniation 

 thence induced is the proximate caufe ; and the mufcular ac- 

 tions are the proximate effect. 



This action of freezing frequently precedes common refpira- 

 tion in new-born children, but I believe not always ; as like the 

 latter it cannot have been previoufly acquired in the uterus. 



It is produced in fome people by fudden light, as by looking 

 up at the iky in a morning, when they come out of a gloomy 

 bed-chamber. It then becomes an aiTociate action, and beiong-i 

 to Clafs IV. i. 2. 2. 



M. M. When it is- exerted to excefs it may be cured by 

 fnuffing ftarch up the noftrils. See Clafs I. i. 2. 13. 



4. Anhelltus. Panting. The quick and laborious breathing 

 of running people, who are not accuitomed to violent exerciie, 

 is occafioned by the too great conflux of blood to the lungs. As 

 the fanguiterous fyilem, as well as the abforbent fyllem, is fur- 

 niflicd in many parts of its eourfe with valves, which in general 

 prevent the retrograde movement of their contained fluids ; and 

 as all thefe veffels, in fome part of their courle, lie in contact 

 with the rnufcles, which are brought into action in running, it 

 follows that the blood mult be accelerated by the intermitted 

 fwelling of the bellies of the mufcles moving over them. 



The difficulty of breathing, with which very fat people are 

 immediately affected on exercife, is owing to the preffure of the 

 accumulated fat on the veins, arteries, and lymphatics ; and 

 which, by diftending the {kin, occafions it to act as a tight ban- 

 dage on the whole furface of the body. Hence when the muf- 

 cles are excited into quicker action, the progrefs of the blood in 

 the veins, and of the lymph and chyle in the abforbent fyllem, 

 is urged on with much greater force, as under an artificial ban- 

 dage on a limb, explained in Art. IV. 2. 10. and in Sect. 

 XXXIII. 3. 2.- Hence the circulation is inftantly quickened to 

 a great degree, and the difficulty of breathing is the confequence 

 of a more rapid circulation through the lungs. The mere-died 

 fecretion of the perfpirable matter is another confequence of 

 thisrapid circulation ; fat people, when at reft, are believed toper- 

 fpire lefs than others, which may be gathered from their generally 1 

 having more liquid (tools, more and paler urine;, and to their 

 frequently taking lefs food than many thin people , and laitly, 

 from the perfpiration of fat people being generally more inodo- 

 rous than that of lean ones ; but when corpulent people are put 

 in motion, the fweat (lands in. drops on theii Ikins, and they 

 ' Vot, II, W Urd 



