ANALYSIS OF LYMPH 155 



the living body. It fills up the spaces between the cells themselves and 

 between the cells and the blood vessels which ramify among the cell masses. 

 The lymph, therefore, is an intermediate fluid between blood plasma on the 

 one hand and the tissue cells on the other, receiving its ingredients by the 

 passage of fluid from the plasma through the walls of the finer blood vessels 

 in the one direction and by the discharge of the substances from the cells 

 themselves in the other. 



The Chemical Composition of the Lymph. Since the chief source 

 of the lymph is the blood plasma, one would naturally expect that its chemi- 

 cal composition would be very similar to that of plasma, which is in fact the 

 case. The variations that are noted in lymph taken from definite sources no 

 doubt have their origin in the fact that the lymph passes through these 

 organs slowly, and that ingredients peculiar to the necessities of the func- 

 tion and growth of the differentiated tissue of the organ are taken from the 

 lymph in special organs. Lymph obtained from a human lymphatic fistula 

 has been analyzed; the figures from Hammarsten are as follows, though 

 considerable variations appear in the analyses from other authorities: 



ANALYSIS OF LYMPH. 



Per cent. 



Water 94-5 to 96 . 5 



Solids 3.5 to 5.5 



Proteins 3.4 to 4.1 



Ethereal extract o . 06 to 0.13 



Sugar o.i 



Salts 0.8 to 0.9 



Sodium chloride -55 to 0.58 



Sodium carbonate 0.24 



Disodic phosphate 0.028 



The most notable fact to be derived from this composition table is the 

 low percentage of proteins present in the lymph. 



The Formation of Lymph. The manner in which the substances in 

 the lymph pass through the walls of the capillaries from the plasma is a 

 question which has been surrounded with considerable difficulty. It was 

 thought by Ludwig and many of his followers that the process involved 

 is merely one of filtration. Certainly the blood-pressure in the capillaries 

 is in the main greater than that of the pressure of the lymph in the surround- 

 ing tissues, and this positive pressure will contribute so much to the direct 

 ingredients of the blood plasma through the capillary walls. It is true, as a 

 matter of experiment, that anything which contributes to an increase in 

 the capillary pressure is very apt to produce an edema of the corresponding 

 tissues. Since the colloidal materials represented by the protein are non- 

 diffusible, one would by this theory expect to find a diminished percentage 

 in the lymph, which is true, though not to the extent which the theory 

 demands. 



