110 PRINCIPLES OF PHYSIOLOGY 



from the breaking up of substances in the 

 tissues substances derived from their physio- 

 logical tear and wear is carried off by a drain- 

 age system of tubes, the lymphatics. The 

 lymph, however, is not thrown out of the 

 body as useless, but, as in the economy of a 

 well-arranged manufactory, it is utilized ; it 

 is carried to lymphatic glands found 

 in many parts of the body and of the 

 same class as those already alluded to as 

 existing in the mesentery. By these glands 

 it is used up, elaborated, as is often 

 said, so as to nourish the protoplasm 

 of those organs, and it is ultimately 

 poured into the blood, either along with 

 the chyle in the thoracic duct, or by a 

 special duct, the lymphatic duct, which 

 joins the venous system at the root of 

 the neck on the right side. Thus the 

 blood receives all the lymph and all the 

 chyle. It also receives cellular elements 

 from the lymphatic glands, from the kind of 

 tissue called lymphoid or adenoid tissue, 

 found in many organs and beneath many 

 mucous membranes, and, in particular, from 



