ORIGIN OF LYMPH. 369 



blood be then passed through the animal's body, still warm, increased 

 lymph will in turn flow from the large lymph-trunks. It thus appears 

 that the tissues are still capable of taking up plasma from the blood 

 for the production of lymph for some time after cessation of the circula- 

 tion. This fact may explain the circumstance that some tissues, as, for 

 example, _the connective tissue, appear to contain more fluid after death 

 than during life, while, at the same time, the blood-vessels have after 

 death given up much of the plasma from their interior. 



Under the influence of curare an increase in the secretion of lymph 

 takes place ; the amount of the solid constituents of the lymph increasing. 

 In the frog large amounts of lymph collect in the lymph-sacs, and this 

 may be due in part to the fact that the lymph-hearts are paralyzed by 

 curare. The production of lymph is increased also in the tissues of 

 inflamed parts. 



ORIGIN OF LYMPH. 

 SOURCE OF LYMPH-PLASMA. 



The lymph-plasma is, in part, a filtrate from the blood-vessels, passing 

 over into the tissues, in accordance with the prevailing blood-pressure. 

 In this process, the salts (penetrating membranes most readily) pass 

 through admixed in approximately the same proportions as the salts in 

 the blood-plasma; the fibrin-factors, to about two-thirds; the albumin, 

 about one-half. As in the case of filtration in general, the filtration of 

 lymph also must increase with increased pressure. 



C. Ludwig and Tomsa were able to demonstrate this by permitting blood- 

 serum to pass through the blood-vessels of an excised testicle under varying 

 pressure, with the result that the transuded fluid from the lymph-vessels was 

 increased or diminished in amount. This artificial lymph exhibited a composi- 

 tion similar to that of natural lymph. The albumin contained in the lymph 

 also increased with increasing pressure. In addition, the metabolic products 

 of the tissues, concerning whose qualitative and quantitative conditions little 

 is known, naturally undergo admixture with the lymph-plasma in the different 

 tissued. 



In part, however, the formation of lymph must be regarded as a 

 secretory process of the cells of the blood-capillaries. 



In favor of this view is the fact that materials injected into the blood (sugar, 

 egg- albumin, peptone, urea and sodium chlorid) pass in concentrated form into 

 the increased lymph ; further, that the blood is capable of maintaining the 

 osmotic tension of its plasma. As a result of this secretory property on the part of 

 the endothelium of the vessels, substances that would disturb the isotonia between 

 the blood-corpuscles and the blood-plasma are quickly eliminated from the blood, 

 including superfluous water. After the injection of peptone, the blood-pressure 

 falls enormously, so that the passage into the lymph cannot be dependent upon 

 this pressure. With increase in the lymph-current, the secretion of urine also is 

 later increased. The lymph-paths may thus be considered as a reservoir that 

 temporarily takes up out of the blood the substances to be eliminated, whence 

 they are then gradually further consumed or excreted. 



According to Heidenhain, there are materials that increase lymph-production, 

 lymphagogues, which are in part effective by causing the passage of fluid from the 

 blood into the lymphatic radicles. Among such agencies are injections into 

 the blood of a decoction of leeches, crab-muscles, mussels, solution of nuclcin, 

 tuberculin, bacterial extracts, bile, physostigmin , pilocarpin and extract of helian- 

 thus. In part they increase the amount of lymph by causing the passage of water 

 from the tissues into the lymph. In this category belong injections into the 

 blood of sugar, urea and salts. Atropin diminishes lymph-production. 

 24 



