AND BLOOD PRESSURE 



159 



the flow of lymph by adding to the total volume of fluid in the 

 vascular system, and thus increasing the capillary pressure and 

 'filtration through the capillary wall. Now in a case of poly- 

 cytha,-mia studied by the writer, the arterial, the venous, and the 

 capillary pressure in the arm, held at heart's apex level, were the 

 same as in himself. There was not a sign of congestion, except a 

 redness of the hands and face and fulness of the veins, and not a 

 trace of oedema in this man. And yet he had a haemoglobin per 

 cent, of 155, 3 times the normal oxygen capacity, 12,000,000 red 

 corpuscles per c.mm. of blood, and a total blood volume 2 times 

 the normal as determined by A. S. Boycott. 



During the temporary arrest of the circulation in the dog the 

 writer has injected rapidly 30 c.c. and more of physiological saline 

 solution into the venae cavae, and observed only a temporary and 

 slight rise of pressure in the venae cavae during the injection and 

 no effect at all on the residual pressure in the arteries ; an experi- 

 ment which shows without question that there is no such thing as 

 a positive " mean hydrostatic pressure " in the vascular system, 

 and that the pressure can be raised in one part without influencing 

 another, owing to the unfilled areas of capillaries, and the roomy 

 capacity of the veins. 



Dog : Cannulx, in Aorta and Vena Cara Superior, connected icith 

 Manometers filled icitli 1 per cent. Sodium Citrate Solution. 



THE EFFECT OF OBSTRUCTING THE VEN\* 



Some remarkable experiments by C. Bolton may be cited here 

 in connection with thess experiments of the writer. Bolton 



