528 ABSOEPTION. 



surround many of the blood-vessels ; for under these circum- 

 stances, endosmotic and exosmotic currents would inevita- 

 bly take place. We have seen, in comparing the composi- 

 tion of the lymph with that of the plasma of the blood, that 

 the constituents of these fluids are nearly if not quite identi- 

 cal ; the only variations being in their relative proportions. 

 This is another strong argument in favor of the passage of 

 most of the constituents of the blood into the lymph. The 

 difference in the proportion of albumen is explained by the 

 fact that this substance is but slightly exosmotic ; and with 

 regard to the proportion of fibrin, it is pretty well estab- 

 lished that, in the blood, this principle is formed by a trans- 

 formation of albumen. The same may occur in the lymph, 

 particularly as the quantity of fibrin has been found to in- 

 crease as the liquid passes from the periphery to the larger 

 vessels. 



One of the most important physiological facts in the 

 chemical history of the lymph is the constant existence of a 

 considerable portion of urea. This cannot be derived from 

 the blood, for its proportion is greater in the lymph, 1 not- 

 withstanding that this fluid is being constantly discharged 

 into the blood-vessels. The urea which exists in the lymph 

 is derived from' the tissues ; it is discharged then into the 

 blood, and is constantly being removed from this fluid by the 

 kidneys. 



The positive facts upon which to base any precise ideas with 

 regard to the general function of the lymph are not very nu- 

 merous. From the composition of this fluid, its mode of circu- 

 lation, and the fact that it is being constantly discharged into 

 the blood, it would not seem to have an important function 

 in the active processes of nutrition. The experiments of Col- 

 lard de Martigny sustain this view, inasmuch -as the quan- 

 tity and the proportion of solid constituents of the lymph 

 were rather increased than diminished in animals that had 



1 WURTZ, written communication, in LOXGET, Traite de Pliytiologie, Paris, 

 1861, tome i., p. 429, note. 



