166 



ADVANCED PHYSIOLOGY 



X Lumph Vessel 



?^/- ^Capillaries 



FIG. 92 DIAGRAM 



Showing the beginning of the lymph vessels 

 and their relation to the capillaries. 



materials which have entered the blood, and the body 

 cells take their nourishment from it. Moreover, the waste 



products which arise in 



the body are ejected from 

 the cells directly into the 



same lymph. The lymph, 

 therefore, serves both to 

 supply the cells with their 

 nourishment, and to re- 

 ceive their waste pro- 

 ducts. It is thus an ex- 

 tremely complicated solu- 

 tion, containing all the 

 material which the body 

 absorbs, and all the excre- 

 tions which the body 

 produces. 



Flow of the Lymph. We may obtain a better idea of the 

 flow of the lymph and of the lymphatic vessels, by making a 

 comparison. Suppose a gravel walk extends from the top 

 to the bottom of a hillside. At the time of a heavy rainfall 

 all the pebbles in the walk will be bathed in the water that 

 runs over them. Let these pebbles correspond to the cells in 

 the extremities of the body, bathed in lymph. As we go 

 down the hill a little distance, we notice the water running 

 together in little shallow streams; no definite channels of any 

 depth will be formed, perhaps, but there will be little rills in 

 which the water runs. These correspond to the beginnings 

 of lymph ducts not as yet definitely walled in. 



As we go farther on down the hill, we find streams of con- 

 siderable size made by the flowing together of the small rills. 

 These larger streams flow in very definite channels, and there 

 are banks on each side whicn keep the water in one route. 

 These definite streams may correspond to the larger lymph 

 ducts, with walls of their o\ti_... All along the course of these 



