ORIGIN OF LYMPH. 413 



(4.) When the total amount of the blood is increased, by the injec- 

 tion of blood, serum, or milk into the arteries, much fluid passes into 

 the tissues and increases the formation of lymph. 



(5.) The formation of lymph still goes on for a short time after 

 death, and after complete cessation of the action of the heart, but only 

 to a slight extent. If fresh blood be caused to circulate in the body of 

 an animal, while it is still warm, more lymph flows from the lymphatics 

 (Genersich). It appears as if the tissues obtained plasma from the 

 blood for a time after the stoppage of the circulation. This perhaps 

 explains the circumstance that some tissues, e.g., connective-tissues, con- 

 tain more fluid after death than during life, whilst the blood-vessels 

 have given out a considerable amount of their plasma after death. 



(6.) The amount of lymph is increased under the influence of curara 

 (Lesser, Paschutin), and so is the amount of solids in the lymph. A 

 large amount of lymph collects in the lymph-sacs [especially the sub- 

 lingual] of frogs poisoned with curara, which is partly explained by 

 the fact that the lymph-hearts are paralysed by curara (Bidder). The 

 amount of lymph is also increased in inflamed parts (Lassar). 



200. Origin of Lymph. 



(1.) Origin of the Lymph-Plasma. The lymph-plasma may be re- 

 garded as fluid which has been pressed through the walls of the blood- 

 vessels by the blood-pressure, i.e., by filtration, into the tissues. The 

 salts which pass most readily through membranes, go through nearly 

 in the same proportion as they exist in blood-plasma the fibrin-factors 

 to about two-thirds, and albumin to about one-half of that in the 

 blood. As in the case of other filtration processes, the amount of 

 lymph must increase with increasing pressure. This was proved by 

 Ludwig and Tomsa, who found that when they passed blood-serum 

 under varying pressures through the blood-vessels of an excised testis, 

 the amount of transuded fluid which flowed from the lymphatics varied 

 with the pressure. This " artificial lymph " had a composition similar to 

 that of the natural lymph. Even the amount of albumin increased 

 with increasing pressure. The lymph-plasma is mixed in the different 

 tissues with the decomposition products, the results of the metabolism 

 of the tissues. 



When the muscles are in action, not only is the lymph poured out 

 more rapidly, but more lymph is formed. The tendons and fascia? of 

 the muscles of the skeleton which are provided with numerous small 

 stomata, absorb the lymph from the muscles. By the alternate contrac- 

 tion and relaxation of these fibrous structures, they act like suction- 

 pumps, whereby the lymphatics are alternately filled, and emptied, while 



