340 DISEASES CLASS III. 2. 1. 12. 



the pulse which sometimes occurs in sleep, are copied from a 

 letter of Dr. Currie of Liverpool to the author. 



u Though rest in general perhaps renders the healthy pulse 

 slower, yet under certain circumstances the contrary is the truth. 

 A full meal, without wine or other strong liquor does not in- 

 crease the frequency of my pulse, while I sit upright, and have 

 my attention engaged. But if I take a recumbent posture af- 

 ter eating, my pulse becomes more frequent, especially if my 

 mind be vacant, and I become drowsy; and, if I slumber, 

 this increased frequency is more considerable with heat and 

 flushing. 



" This I apprehend to be a general truth. The observation 

 may be frequently made upon children; and the restless and fe- 

 verish nights experienced by many people after a full supper are, 

 I believe, owing to this cause. The supper occasions no incon- 

 venience whilst the person is upright and awake; but, when he 

 lies down and begins to sleep, especially if he does not perspire 

 the symptoms above mentioned occur. Which may be thus ex- 

 plained in part from your principles. When the power of voli- 

 tion is abolished, the other sensorial actions are increased. In 

 ordinary sleep this does not occasion increased frequency of the 

 pulse; but where sleep takes place during the process of diges- 

 tion, the digestion itself goes on with increased rapidity. Heat 

 is excited in the system faster than it is expended; and operating 

 on the sensitive actions, it carries them beyond the limitation of 

 pleasure, producing, as is common in such cases, increased fre- 

 quency of pulse. 



" It is to be observed, that in speaking of the heat generated 

 under these circumstances, I do not allude to any chemical evolu- 

 tion of heat from the food in the process of digestion. I doubt 

 if this takes place to any considerable degree, for I do not observe 

 that the parts incumbent on the stomach are increased in heat 

 during the most hurried digestion. It is on some parts of the sur- 

 face, but more particularly on the extremities of the body, that 

 the increased heat excited by digestion appears, and the heat thus 

 produced arises, as it should seem, from the sympathy be- 

 tween the stomach and the vessels of the skin. The parts 

 most affected are the palms of the hands, and the soles of the feet. 

 Even there the thermometer seldom rises above 97 or 98 degrees, 

 a temperature not higher than that of the trunk of the body: 

 but three or four degrees higher than the common temperature 

 of these parts, and therefore producing an uneasy sensation of 

 heat, a sensation increased by the great sensibility of the parts 

 affected. 



" That the increased heat excited by digestion in sleep is the 



