FEEQUENCY AND CHARACTER OF RESPIRATORY MOVEMENTS 485 



this difficulty in some measure, but this procedure cannot be resorted 

 to in human beings unless undertaken as a last means to save life. 

 The manual method of artificial respiration possesses the advan- 

 tage that it can be applied almost immediately. A delay of more 

 than ten minutes should never result, because it is practically impossi- 

 ble to restore life if this period of time is exceeded. Furthermore, it 

 is to be remembered that the body becomes entirely flaccid in the 



FIG. 251. DEVICE TO ILLUSTRATE THE INFLUENCE OF THE RESPIRATORY MOVEMENTS 

 UPON THE FLOW OF THE BLOOD THROUGH THE PULMONARY BLOOD-VESSELS. (HerinQ.) 



A, bell jar; B, rubber membrane closing it; V, soft rubber pouch to imitate the 

 pulm. blood-vessels; GH, arrangement for forcing water through V under a constant 

 pressure; j, manometer connected with " intrapleural space." On inspiration, pro- 

 duced by moving the rubber membrane downward, the intrapleural pressure is de- 

 creased. This gives rise to an aspiration which tends to pull the wall of V outward, 

 facilitating the flow from G to H. 



course of ten or fifteen minutes, 1 and that it is then practically impos- 

 sible to ventilate the lungs by means of pressure with the hands. Res- 

 piration not having been restored within this time, it is advisable 

 to resort to the method of inflation, but the apparatus should be placed 

 in the hands of a thoroughly experienced operator. 



It is a well-known fact that the arterial blood pressure rises during 

 inspiration and falls during expiration, while the venous pressure rises 



1 Liljestrand, Wollin and Nilsson, Skand. Archiv fur Physiol., xxix, 1913, 198. 



