STRUCTURE AND FUNCTIONS OF BLOOD AND LYMPH 269 



another more important origin. In many parts of the Body 

 there are collections of a peculiar lymphoid or adenoid tissue, 

 sometimes in nodular masses (lymphatic glands). This tissue 

 consists essentially of a fine network, the meshes of which are 

 occupied with leucocytes which frequently show signs of division. 

 The meshes of the network communicate with lymphatic vessels 

 and the lymph flowing through picks up and carries off the new- 

 formed leucocytes. The lymph being ultimately poured into the 

 blood, the leucocytes become the colorless corpuscles of the latter; 

 and the migrating cells of the lymph are therefore but lymph- 

 corpuscles restored to it, perhaps somewhat changed during their 

 life in the blood-plasma. 



The lymph flowing from the intestines during digestion is, as 

 already mentioned, not colorless, but white and milky. It is 

 known as chyle, and will be considered with the process of diges- 

 tion. During fasting the lymph from the intestines is colorless, 

 like that from other parts of the Body. 



Lymph is feebly alkaline, and has a specific gravity of about 

 1,045. The chief chemical difference between lymph and blood- 

 plasma is that the former contains somewhat more waste ma- 

 terials and less food stuffs than the latter. This is because the 

 consumption of food by the cells and their production of waste 

 keep slightly ahead of the interchange of these substances between 

 blood and lymph by the processes of filtration and dialysis. 

 Lymph contains carbon dioxid in solution but no uncombined 

 oxygen, the latter substance being taken up by the living cells 

 as fast as it enters the lymph from the blood. 



