598 EXPERIMENTS DEALING WITH 



and short rise in the inferior vena cava and a marked and more 

 prolonged rise in the portal vein. He considered the increased 

 capillary pressure sufficient to explain the whole lymph flow as 

 the result of increased filtration. He further showed that if the 

 plethora be prevented by bleeding the animal previous to the 

 injection, the presence of the crystalloid in the blood failed to- 

 increase the lymph flow. This last observation disposes of Heiden- 

 hain's view of the action of these bodies. 



Starling's explanation of the lymph flow solely as the result of 

 hydrsemic plethora is also no longer tenable. Lazarus-Barlow 

 confirmed Starling's results, but objected to his interpretation of 

 them. He pointed out that the increased lymph flow lasted 

 much longer than the rise in venous pressure. Asher has since 

 shown that the increased lymph flow will continue long after the 

 death of the animal, and must then be independent of capillary 

 pressure. 



Heidenhain's second point, that some time after the injection 

 the percentage of the substance may be greater in the lymph than 

 in the blood, has been confirmed by subsequent observers. But- 

 Cohnstein has pointed out that it is impossible to infer from this- 

 observation that the same difference exists on the two sides of 

 a capillary wall. For, substances injected into the blood take some 

 time to reach the thoracic duct, and will take different lengths of 

 time from different areas. Therefore by examining the lymph in 

 the thoracic duct it is impossible to say what percentage of the 

 substance is present in tissue fluid outside a capillary. He 

 therefore compared, not simultaneous specimens of blood and 

 lymph, but the maximal percentage attained in the lymph, which 

 he found was not higher than that in the blood. This result has 

 been denied by Mendel, who found that the maximal percentage 

 of Nal was greater in the lymph than in the blood, but not if 

 the kidneys were ligatured. 



(5) Injection of Heidenhain's first class of lymphagogues, which 

 included such substances as extract of leeches, mussels, and 

 crayfish, Witte's peptone, egg-albumin, &c. To this list has 

 subsequently been added nuclein, various bacterial products and 

 toxins, and extract of strawberries. Their injection causes an. 

 increased flow of more concentrated lymph. The arterial pressure 

 is either lowered or unaltered. The blood and lymph lose their 

 coagulability, and the blood becomes more concentrated from loss- 



