58 PHYSIOLOGY. 



in the elaboration of the lymjjh, as of the chyk, and the fluid thus 

 formed is likewise a nutritive fluid, being mingled with the chyle in 

 the thoracic duct. So that what is true of chylosis, is also true of 

 lympJiosis, both forming a part of the nutritive operations. 



The lymphatics, however, sometimes take up materials that are 

 not inservient to nutrition, as bile, pus, the venereal and other virus 

 that may be brought in contact with them. But these facts merely 

 prove that the walls of the lymphatics are permeable by such sub- 

 stances, for thin fluids will always enter those vessels that present 

 the thinnest walls and the greatest surface. As this is the case with 

 the lymphatics upon the surface of the body, it explains the phenomena 

 of absorption through that surface. In the lungs and in the intestinal 

 canal, the veins are most numerous, hence these are the recipients of 

 the thin fluids. In both cases the fluids soak in by imbibition. In 

 the case of the absorption of pus, the probability is that the absorb- 

 ents must have been laid open themselves by the ulcerative process, 

 since the pus-globule is too large to have gained admittance in any 

 other way. 



It is difficult to speak with certainty of the source of the matters 

 absorbed by the lymphatics. Their contents bear a close resemblance 

 to the fluid element of the blood, or " liquor sanguinis " in a state of 

 dilution. Dr. Carpenter supposes them to consist of the residual 

 fluid, which, having escaped from the blood vessels into the tissues 

 for their nutrition, is now to be returned to the former. They may 

 also include those particles of the solid frame-work which have lost 

 their vital powers, and are therefore not fit to be retained as compo- 

 nents of the living system, but are not yet so far decayed as to pre- 

 vent their serving a^ materials for reconstruction after being again 

 subjected to the organizing process. 



The same author says further, that if this view of the function of 

 the lymphatics be correct, it follows that we must attribute to the 

 blood-vessels the absorption of the truly effete particles ; and in this 

 there would seem to be no improbability, since we know that the 

 venous blood contains the elements of two important excretions, that 

 of the liver and that of the lungs, in far greater proportion than 

 arterial blood ; and there is also in the former fluid a certain amount of 

 "ill-defined animal principles " that seem ready to be thus thrown off*. 

 The lymph very closely resembles the chyle, the main difference 

 being in their colour, the lymph beino; nearly colourless. Both con- 

 tain the same ingredients, but not in the same proportions, the chyle 

 abounding most in organic elements. Both contain peculiar corpus- 

 cles, and are capable of self coagulation, in fact each may be looked 

 upon as imperfectly elaborated blood. 



The movements of the chyle and lymph in their respective vessels 

 is due partly to vis a ter2;o, but mainly to the contractility of the 

 middle coat. Both sets of vessels are supplied with valves which 

 prevent a retrogade movement. 



