194 LYMPHATIC SYSTEM. 



capable of that turgescency which is necessary to adapt the 

 sentient extremities of the nerves to receive impressions, so I 

 suppose the villi of the intestinal tube are able to exert a similar 

 erection or turgescency, in order to make the small absorbents 

 stand rigidly open, and thereby act like capillary tubes of glass 

 or other hard substances : and perhaps such membranes as the 

 pleura, peritoneum, &c. may be without villi, because such pro- 

 cesses would be less proper for affording the smoothness of sur- 

 face required for the motion of one viscus upon another ; but 

 to answer the same purpose they may have a network of blood- 

 vessels surrounding the absorbing pores^ which reticulation, by 

 its turgescency, may make the pores stand rigidly open as those 

 we have observed upon the villi (LXXXVIII*). But this being 

 a less perfect organization, and used here, merely because the 

 more perfect, or villous, would be incompatible with the mo- 

 tion of the viscera upon those membranes, may, for that rea- 

 son, be more liable to fail in doing its office, and thereby 

 occasion dropsies of those parts ; nothing like which seems to 

 happen to the villi, which do not, as far as we know, ever 

 fail in absorbing chyle so as to occasion a disease. 



The orifices of the lacteals and lymphatics, therefore, by 

 acting as capillary tubes, in consequence of a particular organiza- 

 tion near their beginnings, are capable of absorbing the chyle 

 and lymph ; and as a capillary tube of glass being put into a 

 basin of water will attract the water to a considerable height 

 above the surface of that fluid, so the animal tubes or ab- 

 sorbents, merely by their attractive power, may not only im- 

 bibe but convey the fluid at least as far as the first pair of 

 valves, whose distance from the orifice of the absorbents is pro- 

 bably very small. But whether the force of attraction extends 

 much farther than the first pair of valves may be a question. 

 Some have suspected that these fluids were propelled forwards 

 principally by this attraction, but it is not necessary to admit 

 such a supposition, in order to explain the motion of the chyle, 

 or of the lymph, because the vessels which convey these fluids 

 are believed to have muscular fibres, which being stimulated by 



(LXXXVIII.*) As mentioned in Notes LXXXII and LXXXIII, this doc- 

 trine of absorption is now exploded. The serous membranes are co- 

 vered with smooth pavement-epithelium. 



