66 THE VITAL PROCESSES 



The cells themselves also help to form the lymph, since 

 the water and wastes leaving the cells add to its bulk. 

 These mix with the plasma from the blood, forming the 

 resultant liquid which is the lymph. A considerable 

 amount of the material absorbed from the food canal also 

 enters the lymph tubes, but this passes into the blood 

 before reaching the cells. 



Composition and Physical Properties of the Lymph. 1 As 

 would naturally be expected, the composition of the lymph 

 is similar to that of the blood. In fact, nearly all the 

 important constituents of the blood are found in the lymph, 

 but in different proportions. Food materials for the ceils 

 are present in smaller amounts than in the blood, while im- 

 purities from the cells are in larger amounts. As a rule 

 the red corpuscles are absent from the lymph, but the 

 white corpuscles are present and in about the same num- 

 bers as in the blood. 



The physical properties of the lymph are also similar to 

 those of the blood. Like the blood, the lymph is denser 

 than water and also coagulates, but it coagulates more 

 slowly than does the blood. The most noticeable differ- 

 ence between these liquids is that of color, the lymph being 

 colorless. This is due to the absence of red corpuscles. 

 The quantity of lymph is estimated to be considerably 

 greater than that of the blood. 



Lymph Vessels. Most of the lymph lies in minute cav- 

 ities surrounding the cells and in close relations with the 

 capillaries (Figs. 27 and 30). These are called lymph 

 spaces. Connecting with the lymph spaces on the one 



1 On account of its position in the body, the lymph is not easily collected for 

 examination. Still, nearly every one will recall some experience that has enabled 

 him to see lymph. The liquid in a water blister is lymph, and so also is the liquid 

 which oozes from the skin when it is scraped or slightly scratched. Swelling in 

 any part of the body is due to the accumulation of lymph at that place. 



