CONSUMPTION OF THE LUNGS. 229 



partly, although rarely, to pain during respiration ; and partly, and in- 

 deed chiefly, to fever. As a rule, dyspnoea is only caused by the joint 

 action of several of these factors. Thus the breathing surface may be 

 excessively reduced in area without the patient's feeling any dyspnoea, 

 and without any acceleration of the breathing while the patient is at 

 rest, provided only that neither severe catarrh, pain, nor fever be pres- 

 ent at the same time. Many patients, whose lungs are so much con- 

 solidated and disorganized that scarcely half of their capillaries remain 

 to carry on the process of oxygenation, still breathe at the normal rate 

 as long as they sit still or are lying in bed. This is simply because a 

 healthy person, under ordinary circumstances, needs to employ but a 

 very small portion of his respiratory apparatus, in order to obtain his 

 proper supply of air. Nor ought we to overlook the fact that, where 

 the lung is indurated and disorganized, the surviving vesicles are more 

 strongly distended by an inspiration of ordinary depth, and allow more 

 air to escape upon expiration than do the air-cells of a healthy lung. 

 The increased activity of oxygenation which thus goes on in the re- 

 maining air-cells manifestly compensates, in a great measure, for the 

 deficiency of those which have perished. 



The breathing-surface may be seriously diminished by the presence 

 of miliary tubercles, which, though they may elude physical demonstra- 

 tion, fill up a large number of the disorganized alveoli, and close many 

 of the smaller bronchi. Hence, great rapidity of breathing without 

 dulness on percussion, or bronchial respiration, is one of the most im- 

 portant signs of tuberculous consumption, in the narrower sense of the 

 word. If we find that a patient, whose lungs are more or less solidi- 

 fied and destroyed, but who hitherto has suffered but little, if at all, 

 from shortness of breath, begins to exhibit an increase in frequence of 

 respiration and a distressing dyspnoea, there being no increase in the 

 solidification or destruction of the lung or aggravation of the fever to 

 account for it, there is strong reason to fear the addition of a tubercu- 

 losis to the phthisis which already exists. Cases arise in which we 

 can infer the existence of such a complication, solely from the dispro- 

 portion between the small degree of dulness upon percussion and the 

 extreme frequence of the respiration. . . 



It would be superfluous to explain in detail why the respiratory 

 frequence of a phthisical subject is aggravated by pleuritic pain and 

 by exacerbation or extension of the bronchial catarrh, which accom- 

 panies the malady, or by its complication with the pleuritic effusion, 

 hydrothorax, pneumothorax, etc. That respiration is accelerated by 

 fever is evident. Fever consists of a morbid increase of calorification 

 whereby the body becomes overheated. The necessity for air is aug- 

 mented in fever just as it is augmented by every bodily exertion ; since 



