xiv THE LYMPH 533 



into the lymph ami blood are generated ami multiply in these 

 organs. The most convincing experimental evidence is that 

 given by Briicke. In carnivorous animals the lymphatic glands 

 of the mesentery are all collected into a large seiniluuar mass 

 known as the "pancreas of Asellius," which lies at the root of 

 the mesentery. If a little lymph is collected from the lymphatics 

 of a cat's mesentery, fed on a diet as free from fats as possible, the 

 fluid is clear and contains hardly any corpuscles. If the lymph 

 of the efferent lymphatic of the so-called pancreas of Asellius is 

 examined at the same time, it is seen to be opalescent, and 

 contains a great number of leucocytes. Further, we have un- 

 mistakable pathological evidence of the formation of leucocytes 

 in the lymphatic glands, since hyperplasia of the lymphatic glands 

 is associated with leucaemia, that is, an extraordinary increase of 

 the leucocytes in the blood. 



The mechanism of the escape of leucocytes from the adenoid 

 tissues where they are generated and develop, is rather more 

 complicated in the lymphatic gland than it is in the solitary 

 follicle. It is certain that the smooth muscle fibres of the 

 capsule and trabeculae have here an important function, whether 

 in promoting the lymph stream through the glandular sinuses, 

 or in driving the leucocytes out of the adenoid rete and propelling 

 them into the efferent lymphatics. For when these muscular 

 elements contract (as can be experimentally brought about by 

 electrical excitation of the ganglion), the capsule and the trabeculae 

 exert pressure directly on the circumfollicular sinuses and indirectly ' 

 upon the whole parenchyma of the gland, so that all the lymphatics 

 are emptied like a sc[ueezed-out sponge through the efferent 

 lymphatics. When, on the contrary, the muscle cells relax, the 

 lymph sinuses swell up again, and are filled with lymph (Briicke). 

 In addition to this lymphapoietic function, we may reasonably 

 hold that adenoid tissues in general are the seat of an exchange 

 of materials between the blood and the lymph. We are unable to 

 gauge the physiological importance of this exchange, which may 

 be enormous, since it is impossible to examine the phenomena 

 of absolute deficiency of the lymphatic glands, which are able to 

 act vicariously and supplement each other. It is further probable 

 that many of the katabolic products poured out by the tissues 

 into the lymph stream, which if directly reabsorbed into the 

 blood would exercise a toxic action, are rendered innociious and 

 even beneficial to the organism by the specific activity of the 

 numerous lymphatic glands through which they pass before 

 rejoining the blood. To give an experimental basis to this 

 hypothesis, Asher and Barbera, studied on the dog the effect on 

 arterial pressure and pulse frequency, of injecting into the central 

 end of the carotid either defibrinated lymph from the head or 

 neck (obtained by continuous centripetal massage of those parts, 

 VOL. i 2 M a 



