192 LECTURE VIII. 



notice last time, it is a very essential and important fact 

 that the fibrine which circulates in lymph differs in cer- 

 tain respects from that contained in the blood, which we 

 see on examining different extravasations, or blood drawn 

 from a vein. The fibrine of lymph has this special pecu- 

 liarity, that under ordinary circumstances it coagulates 

 within the lymphatic vessel neither during life nor after 

 death, whilst blood in many instances coagulates even 

 during life, and regularly does so after death, so that 

 coagulative power is attributed to blood as being one of 

 its regular properties. In the lymphatics of a dead ani- 

 mal or human corpse, no coagulated lymph is met with, 

 yet the coagulation takes place directly the lymph is 

 brought into contact with the air, or has changes imparted 

 to it by some diseased organ. 



The explanation of this peculiarity has been attempted 

 in very different ways. For my own part I must still 

 adhere to the view that there is, properly speaking, no 

 perfectly developed fibrine contained in lymph, but that 

 it becomes perfect either by contact with the atmosphe- 

 ric air, or in abnormal conditions by the introduction into 

 it of altered matters. Normal lymph contains a substance 

 which is very readily converted into fibrine, and is, when 

 it has once coagulated, scarcely to be distinguished from 

 fibrine, but which, as long as it continues to circulate 

 with the ordinary stream of lymph, cannot be regarded 

 as really perfect fibrine. This is a substance, of which 1 

 had demonstrated the presence in various exudations, 

 especially in pleuritic fluids, long before my attention had 

 been drawn to its occurrence in lymph. 



In many forms of pleurisy the exudation long remains 

 fluid, and a number of years ago a peculiar case came 

 under my notice, in which on puncturing the thorax a 

 liquid was evacuated which was perfectly clear and fluid, 

 but in a short time after its evacuation had its whole 



