191 1] William J. Gies 273 



II. Factors which directly or indirectly facilitate the con- 



TINUOUS PASSAGE OF LYMPH (WATER AND DISSOLVED SUB- 

 STANCES) FROM THE TISSUE SPACES TO THE BLOOD. 



A. Conditions which directly or indirectly facilitate filtration, 



diffusion, or osmosis, or all of these processes. 



(a) Permeability of the walls of the capillaries. 



(b) Low pressures in the lymph capillaries and venous 

 circulation (as compared with those in the tissue 

 Spaces). 



(c) High pressures in the tissue spaces (as compared 

 with those in the lymph capillaries and venous circu- 

 culation). 



(d) Excretion from the blood of diffusible substances 

 brought from the cells. 



(e) Inward movement of plasma from the blood capil- 

 laries into the tissue spaces. 



B. Special cellular influences in lymph removal. 



(a) Secretory activity of the endothelium of the lymph 

 capillaries. 



(b) Active intracellular production and ejection of prod- 

 ucts arising in tissue metabolism. 



The above-named factors, or some of them, exert influences 

 which, under ordinary conditions, maintain, in any tissue, the 

 normal relations of lymph production and removal. Recent obser- 

 vations suggest that other factors, among them colloidal hydro- 

 philia, cooperate in efifecting the normal relationships (p. 279). 

 It is obvious thät disequilibration of the normal coordination of 

 forces would tend to yield an abnormal result in any tissue, eithfer 

 in the direction of excessive lymph production or of deficiency in its 

 removal, or of both. 



In a recent discussion of "the distribution of Solutions in cardi- 

 ectomized frogs," Meltzer emphasizes his views on the relation -of 

 the flow of liquids in the " tissue spaces " in the f ollowing terms •} 

 "Finally, the Service of the peripheral mechanism may be called 

 into play also when the general circulation, for one reason or an- 

 other, becomes inefficient ; the excess of lymph which is not carried 

 off by the blood capillaries and the lymphatics is then carried f urther 



* Meltzer: Journal of Experimental Medicine, 191 1, xiii, p. 556. 



