LYMPHATIC SYSTEM. 159 



With respect to that fluid which moistens the cellular sub- 

 stance, or cellular membrane, as it is called, I cannot speak 

 with so much precision, since it cannot be collected in animals 

 in health ; but when we consider how great a probability there 

 is of the lymphatic vessels absorbing that fluid, we may suspect 

 that it is similar to what moistens the pericardium, thorax, ab- 

 domen, &c., especially as I have repeatedly observed, that the 

 lymph returning from the extremities by their lymphatic ves- 

 sels coagulates when exposed to the air equally as the lymph 

 nearer the centre of the body. 



Since, then, those fluids in healthy animals coagulate sponta- 

 neously on being exposed to the air, may we not conclude that 

 they resemble the coagulable lymph of the blood at least more than 

 they do the water, or even than they do the serum, which does 

 not jelly on being exposed to the air ? And is it not an argu- 

 ment in favour of this inference, that such a fluid appears fitter 

 for the office of lubrication than mere water, and more similar 

 to the synovia, 'which of all fluids is the best adapted to that 

 purpose? (LXIX.) 



(LXIX.) Professor Miiller,* like Hewson, regards the self-coagu- 

 lating property as essential to lymph. Dr. Davy has favoured me 

 with the following note on the fluid in the lymphatic vessels of the 

 spermatic cord of the ram : " The lymphatic vessels were large, and 

 distended with a colourless fluid ; it did not coagulate spontaneously, 

 but afforded a considerable and rather dense coagulum when treated 

 with nitric acid." In the careful observation of Mr. Lane, b fluid from 

 the lymphatic vessels of the horse coagulated in about ten minutes. 

 This corresponds with my own observations on the contents of the lym- 

 phatics of the dog and horse ; but in some trials the colourless fluid never 

 coagulated spontaneously. It is therefore probable that self-coagulation 

 is not an essential property of lymph. In reference to the statement 

 in the text, that serum does not coagulate on exposure, it will be 

 recollected that certain varieties of serum will coagulate spontaneously 

 when mixed together: see Note xvm, p. 31. Hewson is not just to 

 his own observations, when he compares coagulable lymph, or the fluid 

 of the lymphatics, to synovia. 



For an account of the properties of lymph, see Muller's Physiology, 

 tr. by Dr. Baly, i, 258 et seq. ; Professor Wagner's Physiology, tr. by 

 Dr. Willis, vol. i, pp. 250 et seq. ; Mr. Lane's article, Lymphatic Sys- 

 tem, in the Cyclopaedia of Anatomy and Physiology ; and the Appendix 

 to the English version of Gerber's Anatomy, pp. 95 et seq., Plates xxxii 

 and xxxiii. 



a Physiology, tr. by Dr. Baly, i, 259. b Cyclop. Anat. and Physiol. iii, 219-20. 



