SUMMARY OP THE LYMPH RELATIONS 179 



Summary of the lymph relations. — From the preceding it is 

 evident that the most important action of lymph is to act as a 

 middleman for the exchange of nutrients and wastes between the 

 blood on the one hand and the cells on the other. Furthermore, 

 the waste matter is in turn taken up by the lymphatics, which 

 drain it off into the veins. In cases of dropsy the failure of the 

 drainage system to remove these wastes causes an accumulation 

 of lymph in the spaces, and often causes the body to swell to an 

 enormous extent. This relation of the lymph spaces and lym- 

 phatics also explains why medicines injected under the skin are so 

 quickly distributed to all parts of the body, the lymphatics taking 

 it up and distributing it to the tissues much more quickly than 

 if it had entered the system through the digestive tract. 



Certain parts of the body pour into the lymph more of their 

 wastes and secretions than others, and this accounts for the varia- 

 tion in composition of lymph in different parts of the body, but 

 the foundation of the fluid is the blood plasma. 



