392 OF RESPIRATION. 



be attained by forcibly compressing the trunk on all sides, so as to empty 

 the lungs as much as possible, and then allowing the chest to dilate 

 again, by the elasticity of its walls. In this manner, a large proportion 

 of the carbonic acid may be expelled, and a considerable proportion of 

 fresh air introduced, in the course of a few minutes. If air be blown 

 into the lungs by the bellows, great care must be taken to prevent the 

 employment of too much force, which is likely to produce rupture of 

 the air-cells. 



709. Now when, from the more prolonged action of various causes 

 that impede the due performance of the respiratory function, the aera- 

 tion of the blood in the lungs is insufficient for health, though not such 

 as to produce a complete stagnation of the movement, a variety of 

 results may follow ; of which some, or others, will manifest themselves, 

 according to the condition of the general system, and the peculiarities 

 of the individual. Thus deficient respiration seems to favour the re- 

 tention of fatty matter in the system ; and this not merely in the con- 

 dition of Adipose tissue, which (unless it accumulate to excess) may be 

 regarded as a healthy product ; but also in the place of the normal 

 components of other tissues, as the muscular and glandular, giving rise 

 to the condition which is termed " fatty degeneration." Again, the 

 due elaboration of the fibrine of the blood is undoubtedly prevented by 

 an habitually-deficient respiration ; and various diseases, which result 

 from the imperfect performance of this elaboration, consequently mani- 

 fest themselves. The Scrofulous diathesis is thus frequently connected 

 with an unusually small capacity of the chest. Further, an habitual 

 deficiency of respiration may impede, though it does not check, the cir- 

 culation in the lungs ; and thus a tendency arises, in various pulmonary 

 diseases, to an overloading of the pulmonary arteries, to a dilatation of 

 the right cavities of the heart, and to a congestion of the venous 

 system in general, as marked by lividity of the surface, by venous pul- 

 sation, &c. This state may result, not merely from obstruction in the 

 lungs themselves, but from deficiency of the respiratory movements, 

 consequent upon torpidity of the medulla oblongata (as in apoplexy 

 and narcotic poisoning), or upon partial interruption of the nervous 

 circle requisite for all reflex movements. Thus when the par vagum is 

 divided, the number of respiratory movements is greatly diminished, 

 and a partial stagnation of the blood in the lungs is the result. The 

 same happens in certain forms of typhoid fever, in which the respi- 

 ratory movements are preternaturally slow, in consequence of torpidity 

 of the medulla oblongata. Now in this state, an effusion of the watery 

 part of the blood into the air-cells of the lungs (as in other cases of 

 obstructed circulation) is very liable to occur; and when the lungs are 

 thus loaded with fluid, the respiratory process is still more impeded, 

 and the disorder has thus a tendency to increase itself. 



