606 EXPERIMENTS DEALING WITH 



It is unnecessary to invoke secretion by the capillary wall to 

 explain the phenomena, as Hamburger did. 



During the death of a cell the disproportion between the 

 osmotic pressures of its total income and output must be great. 

 In this is probably to be found the explanation of the post-mortem 

 flow observed by Hamburger. It will also take part in producing 

 the post-mortem flow found to take place by Asher after the 

 injection of sugar, and by Mendel and Hooker after injections 

 of strawberry extracts or peptone. 



We may therefore adopt the working hypothesis that tissue 

 activity alters lymph flow by physical means, and we shall 

 consider the process in detail when we discuss how the tissues 

 are nourished. 



EXPERIMENTS DEALING WITH LYMPH ABSORPTION 



Absorption from the Connective Tissue Spaces. There are many 

 old and recent observations to show that dyes, salts, and other 

 foreign substances in solution are rapidly taken up by blood- 

 vessels, when introduced into tissues. This absorption by blood- 

 vessels is due really to diffusion taking place between the extra- 

 vascular fluid and the blood as long as any difference in their 

 composition exists. 



Heidenhain denied that it was possible for the blood-vessels 

 to absorb normal extravascular fluid, because blood only differed 

 from tissue fluid in containing more proteid, and therefore it was 

 impossible for this fluid to return to the blood-vessels by any 

 process of diffusion or absorption. 



Starling was the first to offer conclusive proof that the blood- 

 vessels can absorb an isptonic salt solution. He carried on an 

 artificial circulation of a dog's own defibrinated blood separately 

 through each hind leg, one of which was made artificially dropsical 

 by the injection into it of a sodium chloride solution isotonic 

 with the circulating fluid, and the other as a control. The serum 

 was circulated from twelve to twenty-five times, and the per- 

 centage of oxy-hsemoglobin and total solids were estimated in it 

 before the experiment and in the fluid which had circulated 

 through each of the legs. He found that the serum which had 

 circulated through the control leg had become slightly concentrated, 



