548 



Messrs. J. F. Twort and L. Hill. Pulmonary 



probably the same when he discovered that fatigued frog's muscle swells up 

 when placed in water, to a much greater extent than resting muscle. He 

 observed also that sufficient exposure to an atmosphere of oxygen restores to 

 the muscle in a marked degree the osmotic character of resting muscle. It 

 might, therefore, have been supposed that a vigorous circulation of blood 

 through the muscle would have prevented the swelling which we have 

 observed. The fact, however, appears to be that muscle is capable of out- 

 running its oxygen supply with great ease, and this is probably especially 

 true of frog's muscle, in which the opportunities afforded for the acquisition 

 of oxygen are much smaller than in the case of mammalian muscle. 



In comparing our result with that of Fletcher, it must be borne in mind 

 that his phenomenon was probably a purely osmotic one ; ours may involve, 

 or may not, also some change in the permeability of the vessel walls. 



The Effect of the Depth of Pulmonary Ventilation on the Oxygen 

 in the Venous Blood of Man. 

 By J. F. Twort and Leonard Hill, F.E.S. 



(From the Physiological Laboratory, London Hospital Medical College, and 



Eesearch Fund.) 



(Received January 21, 1915.) 



We have sought to gain evidence as to whether the arterial blood is 

 saturated with oxygen during its passage through the lungs when the 

 breathing is shallow and the subject lying at rest. Incidentally we have 

 made some observations on : — (1) The effect of work. (2) The local applica- 

 tion of heat or cold on the gases in the venous blood. 



As means have not been devised for obtaining safely samples of normal 

 arterial blood from man, we have been obliged to content ourselves with 

 samples of venous blood collected from the veins of the arm. 



The samples have been collected for us with strict aseptic precautions by 

 Dr. James Mcintosh, and in some cases by Dr. Paul Fildes. Their daily 

 practice in collecting blood samples from patients has made our colleagues 

 skilful in the technique of this small operation. We owe them our best 

 thanks for their help. 



Neither ligature nor compression was applied to the arm. The needle of 

 the syringe was passed straight into the vein ; the arm of the subject rested 

 upon the couch and remained covered with the sleeve until the moment of 



