ENTRANCE OF AIR INTO TEINS. 577 



into the areolar tissue of the lungs, constituting interlobular 

 emphysema, and that the inspiratory movement was performed 

 with greater difficulty than the expiratory. 



Tlie Cause. — " Owing to the tendency to the formation of a 

 vacuum in the pericardium during inspiration, there is, during 

 that process, a suction action, called by some ' venous inspira- 

 tion,' in the veins within and near the thorax, extending to a 

 limited extent only, and ceasing where the coats of the veins 

 collapse. The space in which this suction action exists is that 

 in which venous flux and reflux are perceptible. Accordingly, 

 it is found that the accident has always occurred when veins 

 have been opened in the cervical and brachial regions." — 

 (Spence.) 



To prevent the occurrence of this accident, after the operation 

 of phlebotomy, it is only necessary to remove the pressure from 

 the vein slowly and carefully; but should it occur, and not 

 prove immediately fatal, the treatment should be directed to 

 maintain an adequate supply of blood to the head. For this 

 purpose stimulants are to be administered ; and if the animal 

 falls, he is to be kept in the recumbent position ; frictions are to 

 be applied to the extremities ; and should the urgent symptoms 

 pass away, the treatment is to be conducted with the view of 

 preventing the occurrence of inflammation of the lungs, a sequel 

 which, experience has shown, is apt to ensue. 



The subject has been carefully investigated by a commission 

 appointed by the French Academy, and by the labours of 

 Magendie, Amussat, Wattman, and Cormack. 



2p 



