798 PROXIMATE CAUSE OF PHTHISIS. 



feebled by impure air or impoverished diet, want 

 of exercise, and the depressing emotions, exposure 

 to a cold atmosphere, a shower of rain, or to damp 

 night air, with thin clothing, after the body has 

 been fatigued with exertion, or weakened by sit- 

 ting in a crowded assembly, the capillaries of 

 the lungs are so far debilitated, that the free cir- 

 culation of blood through them is greatly ob- 

 structed, respiration, and sanguification are dimi- 

 nished, attended with cold extremities, derange- 

 ment of all the secretions, and general loss of 

 strength, owing to the impoverished condition of 

 the blood, which is no longer capable of duly 

 nourishing the solids. In this state, the cohesion of 

 the pulmonary capillaries is so far overcome, that 

 an effusion takes place into the air cells, of serum, 

 albumen, and lymph, which are gradually con- 

 verted into tubercles,* that vary from the size of 



* It was supposed by Hippocrates, that all diseases of the 

 throat and lungs were owing to the excess of phlegm, and that 

 its effusion into the air cells gave origin to the formation of tu- 

 bercles, which on putrifying became pus. Within the last hun- 

 dred years, it has been the fashion to regard tubercles as the 

 cause of phthisis. But if it be true, that the tubercular and scro- 

 phulous diathesis is comparatively rare in tropical and warm cli- 

 mates, like all cutaneous and pulmonary diseases, they must be 

 regarded as secondary effects arising from exposure to cold, which 

 is also the cause of excess in the quantity of phlegm. According 

 to Dr. Alison, above one third of the deaths in Edinburgh under 

 fifteen years of age, are from scrophulous diseases, which are well 

 known to be still more prevalent in the north of Europe, and more 

 so in all the higher latitudes during winter than summer. 



