400 CHARACTERS OF LYMPH. [BOOK n. 



The Characters of Lymph. 



237. As it slowly flows from its origin in the tissues to 

 the mouth of the thoracic duct (we may for simplicity's sake 

 omit the right lymphatic trunk) the lymph is subjected to the 

 influence of the lymphatic glands, and is possibly affected by 

 the walls of the lymph- vessels. Moreover the lymph coming 

 from one tissue differs more or less in certain characters from 

 the lymph arising in another tissue, just as the venous blood of 

 one organ differs from the venous blood of another organ ; and 

 these differences may be exaggerated by the activity of the one 

 or other tissue. Of these differences by far the most striking 

 is that between the lymph coming from the alimentary canal 

 during active digestion and known as chyle, and the lymph 

 coming from other parts of the body. When digestion is not 

 going on, and when consequently no considerable absorption of 

 material from the alimentary canal into the lacteals is taking 

 place, the fluid flowing along the lacteals is lymph, not differ- 

 ing from the lymph of other regions to any marked degree. 



The fluid accordingly which flows along the thoracic duct in 

 an animal which has not been fed for some considerable time 

 may be taken as illustrating the general characters of lymph. 

 The contents of the thoracic duct may be obtained by laying 

 bare the junction of the subclavian and jugular (in the dog 

 the junction of the axillary and jugular) veins, and introducing 

 a cannula into the duct as it enters into the venous system at 

 that point. The operation is not unattended with difficulties. 



Lymph, so obtained, is a clear transparent or slightly opales- 

 cent fluid, which left to itself soon clots. The clotting is not 

 so pronounced as that of blood, but clotting is caused as in 

 blood by the appearance of fibrin. The fibrin which is formed 

 though scanty, -05 p.c., is identical apparently with that of 

 blood, and as far as we know, all that has been said previously, 

 14 23, concerning the nature of clotting in blood applies 

 equally well to lymph. 



Examined with the microscope lymph contains a number of 

 corpuscles, lymph-corpuscles, which in all their characters so 

 far as is at present known are identical with white blood cor- 

 puscles ; they vary in size from 5 ^ to 15 /i, and the smaller 

 corpuscles are much more abundant in lymph than in blood. 

 Like the white blood corpuscles of blood they exhibit amoeboid 

 movements. Their number varies in different animals, and, 

 apparently, in the same animal, according to circumstances ; 

 on the whole perhaps it may be said that lymph corpuscles are 

 about as numerous in lymph as white corpuscles in blood. 

 Even when every care is taken to avoid admixture with blood, 

 lymph, and especially chyle, not unfrequently contains a cer- 



