ABSORPTION 411 



the lymphatics of the pancreas, as well as a flow of pancreatic 

 juice. But it has been shown that the increased production of 

 lymph is not due to the secretin at all, but to lymphagogue 

 substances, including albumose, extracted with the secretin 

 from the intestinal mucous membrane. A solution of secretin 

 can be prepared which causes a considerable increase in the 

 secretion of pancreatic juice and bile, but no augmentation what- 

 ever in the flow of lymph from the thoracic duct. Again, it was 

 asserted that peptone, a noted lymphagogue, produces a great 

 increase in the biliary secretion. It has been demonstrated, 

 however, that the action of the peptone is merely to cause 

 expulsion of the contents of the gall-bladder by the mechanical 

 effect of the swelling of the liver, and not at all to stimulate 

 the liver-cells to form more bile. For it produces no effect 

 on the flow of bile if the gall-bladder be emptied or the cystic 

 duct tied before the injection (Ellinger). That active salivary 

 secretion is not accompanied by increased lymph-flow from 

 the lymphatics of the salivary glands has been mentioned above. 

 Nevertheless, we may safely assume that the activity of the 

 organs does make a contribution to the lymph to its solids, 

 if not in any important degree to its water-content, although 

 to say that they alone are concerned in its formation, to 

 the exclusion of the capillaries, is altogether an over-state- 

 ment. The waste-products of the tissues pass into the lymph, 

 and possibly, as Koranyi suggests, may, by increasing its mole- 

 cular concentration, cause the passage of some water into it from 

 the blood. Or the decomposition of the large protein molecules, 

 which in tissue metabolism are breaking down into numerous 

 smaller molecules, may entail an increase of osmotic pressure in 

 the cells themselves, which in turn may lead to withdrawal of 

 water by the cells from the tissue liquid. The osmotic pressure 

 of the liquid may thus rise, and water may pass into the tissue 

 spaces from the blood. The molecular concentration of lymph 

 (except in anaesthetized animals as mentioned above) is in 

 general somewhat greater than that of blood-serum e.g., 

 in one observation A of serum was 0*605 C., and of lymph 

 0-610 C. For the solid tissues, the freezing-point of which, 

 however, cannot be as satisfactorily determined as that of 

 liquids, the following values of A were obtained : Brain, 0-65 ; 

 muscle, 0-68 ; kidney, 0-94 ; liver, 0-97 ; while for blood it was 

 0-57 (Sabbatani). 



To sum up, we may say that while the physical processes of 

 filtration, osmosis and diffusion may play a part in the passage of 

 water and solids through the walls of the blood capillaries, as well 

 as from the tissue-cells into the tissue spaces, and from these spaces 

 into the lymph capillaries, there is much which they leave unex- 



