332 CHYLE, LYMPH, TRANSUDATES AND EXUDATES. 



especially great interest, and they may, according to HEiDENHAiN, 1 be 

 divided into two different chief groups. The lymphagogues of the first 

 series extracts of crab-muscles, blood-leech, anodons, liver and intestine 

 of dogs, as well as peptone and egg albumin, strawberry extracts, meta- 

 bolic products of bacteria and others cause a greatly increased secre- 

 tion of lymph without raising the blood-pressure, and in this way the 

 blood-plasma becomes poorer in proteins and the lymph richer than before. 

 For the formation of this lymph, which HEIDENHAIN designates blood- 

 lymph, we must admit with him that a special secretory activity of the 

 capillary-wall endothelium exists. The lymphagogues of the second 

 series, such as sugar, urea, sodium chloride, and other salts, also cause 

 an abundant lymph formation. The blood, as well as the lymph, thereby 

 becomes richer in water. This increased amount of .water depends, 

 according to HEIDENHAIN, upon an increased delivery of water by the 

 tissue-elements, and this lymph is chiefly tissue-lymph, in his opinion. 

 Diffusion is no doubt of great importance in the formation of this lymph, 

 but the secretory activity of the endothelium is also of importance, at 

 least for certain bodies, such as sugar. 



In the past, the formation of lymph was explained in a purely physical 

 way by the united action of filtration from the blood and the osmosis 

 between the blood and tissue-fluid. Later HEIDENHAIN and also HAM- 

 BURGER ascribed a special activity to the capillary endothelium, assum- 

 ing that they take part in the formation of lymph in a secretory manner. 



Another view, which besides the physical processes is also of especial 

 physiological moment in the explanation of lymph formation, was sug- 

 gested by ASHER and his collaborators (BARBERA, GIES, and BUSCH). 

 According to them the lymph is a product of the work of the organs; 

 its amount is dependent upon an increased or diminished activity of the 

 organs, and the lymph is therefore a measure of the work in these. The 

 close relation between lymph formation and the work of organs has also 

 been shown for several of them, especially for the liver. STARLING has 

 shown that after the introduction of lymphagogues of the first series, 

 chiefly liver lymph is secreted, which he claims is a proof against HEIDEN- 

 HAIN' s view, and he explains the increased permeability of the vessel 

 wall by the fact that these bodies have an irritating, poisonous action. 

 On the contrary, ASHER explains this increased lymph flow by the state- 

 ment that the substance in question as well as those influences which 

 incite the activity of the liver produces an increased formation of lymph 

 in these organs. This view is supported by experiments upon the action 



1 Heidenhain, Pfl tiger's Arch., 49; Hamburger, Zeitschr. f. Biologie, 27 and 30. 

 See especially Ziegler's Beitr. zur Path. u. zur allg. Pathol., 14, 443; also Arch. f. 

 <Anat. u.) PhysioL, 1895 and 1896. 



