LYMPH FLOW 9 



lishment of continuous lymphatic channels, by which it is 

 subsequently conveyed to the venous circulation. To what 

 extent independent endothelial-lined and closed lymph sacs 

 of the embryo, other than the subocular sacs of the trout, 

 function in a similar manner during ontogeny, is a question 

 still to be determined. In any event, we can now demonstrate 

 in the living trout embryo that lymph in the interstitial 

 spaces received from the blood capillaries collects in certain 

 closed lymph sacs which are at first independent of the veins 

 and of other lymphatics. 



It was largely through these researches on the development 

 of the lymphatic system that the writer was led to study the 

 problem of the flow of lymph between the blood capillaries 

 and the lymphatics; and his investigation is set forth in the 

 following pages. The study concerns chiefly the capacity of 

 frog skin (whether it be the skin of the living animal or skin 

 detached from the body) to transport water through itself 

 under various experimental conditions. Many observations 

 pertinent to the present study have been made by previous 

 writers ; the main feature of the present work is its analysis 

 of an extended series of observations, which indicates a pos- 

 sible explanation of the continuous flow of fluid between the 

 blood capillaries and the blindly ending capillaries of the 

 lymphatics. 



We know that water is chiefly supplied to the body of the 

 living frog by osmosis through the integument into the sub- 

 cutaneous lymph sinuses. Reid, 4 Overton, 5 and Maxwell 6 

 have observed that when a skin glove, with the outside of the 

 skin turned outward, is filled with a Ringer's solution and 

 suspended in the same solution, water may, in spite of the 

 equilibrium of osmotic pressure, be transported through the 

 skin into the glove. 



4 Reid, E. W. 1890 Osmosis experiments with living and dead membranes. 

 Jour. Physiol., voL XI. 



8 Overton, E. 1904 Neununddreissig Thesen iiber die Wasserokonomie der 

 Amphibien und die osmotischen Eigenschaften der Amphibienhaut. Verhl. d. 

 Phys.-med. Ges. zu Wurzburg, N.F., Bd. 36. 



Maxwell, S. S. 1913 On the absorption of water by the skin of the frog. 

 Amer. Jour. Physiol., vol. 32. 



