792 RATIONALE OF DISEASES OF 



cough, pneumonia, bronchitis, pleurisy, and phthi- 

 sis, are so much more prevalent in the higher 

 latitudes during winter than summer, and at all 

 seasons than in tropical and warm climates ? 



I answer, because the pulmonary air cells and 

 schneiderian membrane, present an extensive sur- 

 face to the atmosphere ; and that in cold climates, 

 they are exposed to the paralyzing influence of 

 a low temperature, more constantly than any 

 other part of the body. The consequence is, that 

 as animal heat is the immediate cause of all vital 

 action, the chemical function of the lungs, sangui- 

 fication, and circulation, are diminished, consti- 

 tuting the first link in the chain of the morbid 

 phenomena, which are essentially the same in all 

 cases, modified, however, by the condition of the 

 system, the nature of the part more immediately 

 affected, and the greater or less intensity of the 

 exciting cause. 



If the exposure is slight, or of short duration, 

 and the lungs are sound, the result is what we 

 denominate a common cold, which presents in 

 a mitigated form all the essential conditions of 

 fever. It is generally brought on by sitting in a 

 cold room, exposure to damp or cold night air, 

 a shower of rain, getting the feet wet, and often 

 by sitting in a current of air when fatigued by 

 exercise. The first effect of which is, that the 

 capillary vessels of the lungs and schneiderian 

 membrane are weakened, the circulation through 



