xiv THE LYMPH 515 



cardium, tunica vaginalis of testicles, etc., normally contain only 

 a small quantity of lymphatic effusion, sufficient to lubricate 

 the walls. But under abnormal conditions, particularly with 

 mechanical obstruction of the venous circulation, and with marked 

 delay in the circulation, however produced, it is possible to collect 

 large quantities of fluid from these cavities, which differs con- 

 siderably in composition from the lymph obtained from the 

 thoracic duct. It has a low specific gravity (1008-1015) ; contains 

 a minimum amount of proteins (2'2-7*3 per cent) ; is almost 

 free of corpuscles ; does not, generally speaking, coagulate spon- 

 taneously, but since it contains fibrinogen, coagulates on the addi- 

 tion of thrombin, or fluids which contain it (see Chap. V. 6). 



Bainbridge, Asher, Mendel and Hooker noted that, under 

 given experimental conditions, the flow of lymph from the 

 cannula inserted in the thoracic duct continues for a not 

 inconsiderable time after death. Jappelli and D' Errico have 

 recently demonstrated that a post-mortem flow of lymph occurs 

 in every case, but is especially persistent when the death of 

 the animal occurs instantaneously (electrocution) and without 

 haemorrhage. According to the same authors small quantities of 

 post-mortem lymph are constantly obtained from the cervical and 

 brachial trunks as well. It is, however, mainly, though not 

 exclusively, visceral in origin. 



Post-mortem lymph differs essentially in its characteristics from 

 the normal by : 



(a) Its osmotic pressure, which gradually increases up to and 

 beyond that of normal blood ; 



(6) Its gradually decreasing electrical conductivity ; 



(c) Its increased viscosity and greater content of solids ; 



(d) Peculiar changes in the velocity of outflow ; 



(e) Its appearance, now more haematoid, now more chylous, 

 always more turbid. 



These researches of D' Errico and Jappelli show plainly that 

 post-mortem lymph is not pre-formed lymph. Hence it becomes 

 necessary to admit that the processes of lymphagenesis, whatever 

 these may be, continue for .some time after death. Nor should 

 this be surprising when we reflect that after somatic death there 

 is no instantaneous abolition of all the haeniodynaniic, osmotic, 

 cellular, and other factors which are invoked in explaining the 

 formation of lymph in the living animal. 



III. The lymph contained in the lymphatic system is in 

 continual movement from the roots to the large trunks, like the 

 blood in the veins into which these empty themselves. This is 

 proved by the fact that ligation of a lymphatic trunk produces 

 filling and swelling below and comparative evacuation above, as 

 in the veins ; and that the valves in the lymphatics as in 

 the veins impede the centrifugal course of the fluids within 



