AERESTED PULMONARY CIRCULATION 865 



hindered from passing tln^ougli the lungs. In consequence of 

 tlie obstruction in front, the ])lood accumulates in the riglit side 

 of the heart, and distends tlie large veins. It passes so slowly 

 through the pulmonary vessels, that, although it is laden with 

 carbonic acid, and is quite able to give off' this gas and to take 

 up oxygen,* the air which is expired contains but a small pro- 

 portion of the carbonic acid which it would do in health.f So 

 little blood reaches the left ventricle, that all that it can send 

 out at each systole hardly causes a wave in the arteries. The 

 pulse therefore becomes weak and imperceptible, not only in 

 the radial, but in large vessels like the brachial ; and the 

 arteries, when cut across, hardly bleed at all. J The arterioles, 

 and probably the capillaries, become empty ; or, as some term 

 it, the vital turgor disappears ; and this empty state of the 

 vessels, along with the drying of the tissues already alluded to, 

 causes the face to become pinched and shrunken, the fingers 

 shrivelled, and the skin to lose its wonted elasticity. § From 

 the want of any fresh blood from behind to force it on, rather 

 than from the obstruction in front, the blood stagnates in the 

 venous ratlicles, and becomes almost completely deoxygenated, 

 giving a livid hue to the surface ;!| and when a vein is opened, 



* I have not been able to find direct experiments on the amount of carbonic 

 acid contained in the venous blood in cholera, nor on its power to give off this 

 gas and absorb oxygen, but I infer that it contains much carbonic acid, from its 

 extremely dark colour ; and that its power of undergoing respiratory changes is 

 not destroyed, from the fact that it becomes red on exposure to air. See Parkes 

 on Cholera, p. 113. 



t Raver, Gazette Medicale, 1832, p. 278, and several authors quoted by him. 



X Diefft^nbach, quoted by Griesinger, Virchow's Handbuch der Pathologie und 

 Thernpie, Bd. ii, Abth. 2, p. 327, and by Magendie, Gazette Medicale, 1832, 

 p. 253. Magendie attributes the emptiness of the arteries, and Grriesinger the 

 slow passage of blood through tlie lungs, to weakness of the heart ; but it seems 

 much more probable that they are due to obstruction of the pulmonary circula- 

 tion, as Parkes has shown that the heart sometimes continues to beat with 

 considerable vigour during collapse, and the second sound of the heart becomes 

 inaudible while the first can still be heard. Now the first sound is caused 

 almost entirely by the contraction of the musculnr walls of the heart (Ludwig 

 and Dogiel, Ludwig' s Arheiten, 18G9, p. 78), and it disappears y?r*# in cases of 

 weakneMs of the organ, as in fever ; but the second sound is caused by the closure 

 of the sii:moid valves. 



§ Niemeyer, Practice of Medicine ; translation. London, 1871, vol. ii, p. 637. 



[| Griesinger, op. cit., p. 328. 



