318 THE ADRENAL, GENERAL MOTOR, AND VAGAL SYSTEMS. 



lower specific gravity. Inorganic salts, the chlorides prepon- 

 derating, also correspond to those of the plasma. Being a 

 vehicle for various substances, its constituents are variable 

 quantities, and the conflicting analyses published are thus ac- 

 counted for. Stewart says, in this connection: "Lymph has 

 been defined as. blood without its red corpuscles (Johannes 

 Muller); it is, in fact, a dilute blood-plasma, containing leu- 

 cocytes, some of which (lymphocytes) are common to lymph 

 and blood, others (coarsely granular basophile cells) are absent 

 from the blood. The reason of this similarity appears when 

 it is recognized that the plasma of lymph is derived from the 

 plasma of blood by a process of physiological filtration (or 

 secretion) through the walls of the capillaries into the lymph- 

 spaces that everywhere occupy the interstices of areolar tissue. 

 But, in addition to the constituents of the plasma, lymph ap- 

 pears to contain certain toxic substances produced in the me- 

 tabolism of the tissues and destroyed in the lymphatic glands. ' r 



It now seems probable that the intestinal tract, being one 

 of the two regions most exposed to toxics, the villi not only 

 have for their function to absorb chyle, but to protect the or- 

 ganism. The lacteal is the recognized absorption organ for 

 emulsified fats. As we view the process involved, the fat-con- 

 taining fluids, as soon as they reach the basement membrane, 

 are first submitted to the asepticizing influence of its endo- 

 thelial cells. They are then submitted to the next process of 

 epuration, and probably chemically transformed in the lym- 

 phoid layer Kolliker's cytogenous layer immediately be- 

 neath, in which leucocytes, and, therefore, antitoxic substances, 

 are constantly being formed. When it finally reaches the lacteal, 

 it again meets endothelial walls, and when through these and 

 in the lacteal, must run the gauntlet of an accumulated array 

 of fresh leucocytes from the cytogenpus layer. The chyle, 

 therefore, is met as soon as it enters the organism by all the 

 latter's protective resources: phagocytes, stellate or connective- 

 tissue cells, endothelial cells, and finally the oxidizing sub- 

 stance, the latter probably serving here to convert products of 

 local metabolism and other toxic materials into inert bodies. 



The villi, which thus absorb all nutrient substances as- 

 similated by the organism whether by their venous stems or 



