ABSORPTION FROM CONNECTIVE TISSUES. 303 



were able to absorb fluids as well as solids in fine suspension or solution. 

 A number of reasons for this conclusion are given by Johannes Miiller, 

 and I may quote some of these as an example of the arguments by 

 which older anatomists, such as Hunter and Hewson, had come to hold 

 this opinion. In the first place, the lymphatics often become painful, 

 red streaks appear in their course, and the neighbouring lymphatic 

 glands become swollen after the application by friction of irritating 

 matters to the skin. Mascagni asserted that, in animals which died 

 from pulmonary or abdominal haemorrhage, the lymphatics of the pleura 

 and peritoneum were filled with blood (Miiller discredits this assertion as 

 " extravagant "). Mascagni and Soemmering observed bile in the 

 lymphatics coming from the liver, in cases where the bile ducts were 

 obstructed. Tiedemann and G-melin, 1 after tying the ductus choledo- 

 chus in dogs, found the lymphatics of the liver filled with a fluid of a deep 

 yellow colour. The lymphatic glands through which these lymphatics 

 passed were yellow, and the yellow fluid taken from the thoracic duct con- 

 tained biliary constituents. The effect of this and similar evidence on the 

 minds of the anatomists in Hunter's time was rather curious. Since 

 nature had provided a system the lymphatics on purpose to serve 

 the office of absorption, it was considered in the highest degree 

 improbable that this office would also be carried out by the veins, and 

 William and John Hunter, as the result of experiments on absorption 

 from the intestines, concluded that the veins take no part in absorption. 

 To this view of exclusive power of absorption possessed by the 

 lymphatics, it was objected that animals exist which possess neither 

 lacteals nor lymphatics. It was therefore regarded as a brilliant victory 

 for the hypothesis, when Hewson demonstrated the existence of lacteal 

 and lymphatic vessels in birds, reptiles, and fishes. 



Subsequent researches, especially by Magendie, 2 have shown, how- 

 ever, that absorption from all parts of the body can be effected by 

 blood vessels as well as by lymphatics. Magendie's researches have 

 been continued and extended of late years by Ascher 3 in the case of 

 the connective tissues of the lower limbs, by Tubby and myself 4 in the 

 case of the pleural and peritoneal cavities. We found, for example, 

 that, after injecting methylene-blue or indigo -car mine into the pleura, 

 the dye-stuff appeared in the urine within five minutes, whereas the 

 lymph presented no trace of blue for another twenty minutes, or even 

 two hours. It is evident that in this case the dye must have been 

 taken up by the blood vessels and not by the lymphatics, and that 

 this vascular absorption takes place with extreme rapidity. In a later 

 series of experiments, Leathes 5 has shown that, after introduction of 

 various salt solutions into the serous cavities, an interchange of con- 

 stituents takes place directly between the blood and the injected fluid, 

 so that the latter in a very short time becomes isotonic with the blood 

 plasma. Now, in this mode of absorption by the blood vessels the so- 

 called absorption really consists in an interchange between blood and 

 extravascular fluids an interchange apparently dependent entirely 

 upon processes of diffusion between these two fluids. So long as any 



1 Quoted by Muller (Baly's translation, vol. i. p. 242). 



2 Precis elementaire de physiologic," Paris, 1836. 



* Ztschr.f. Bid., Miinchen, 1893, Bd. xxix. S. 247. 



4 Journ. PhysioL, Cambridge and London, 1894, vol. xvi. p. 140. 



5 Ibid., 1895, vol. xviii. p. 106. 



