ABSORPTION OF PARENCHYMATOUS EFFUSIONS. 373 



of excitation of the lymph-hearts is to be sought in Waldeyer's ganglia. Irrita- 

 tion of the skin, the intestine and the blood-heart gives rise to a reflex influence, 

 partly acceleration, partly retardation of the beat, which does not affect the sacrai 

 heart if the coccygeal nerve, which connects the posterior lymph-heart with the 

 spinal cord, is divided. Strychnin-convulsions accelerate the beat, as does also 

 irritation of the spinal cord by heat, while it is diminished by cold. The heart 

 that has ceased to beat in consequence of exposure or of the action of muscarin, but 

 not resting in consequence of destruction of its nerves, can be excited to renewed 

 pulsation by increased filling. Antiar paralyzes the lymph-hearts and the blood- 

 heart; curare, the former only. In other amphibians, two lymph-hearts have 

 been found; and one or two in the ostrich and the cassowary, in some web-footed 

 birds, as well as in the chicken-embryo; in fish they have been found in the tail, 

 as, for example, in the eel, where their pulsation visibly affects the adjacent 

 veins. 



The nervous system has a direct influence upon the movement of 

 the lymph through innervation of the muscles of the lymphatics, the 

 lymph-glands, and, when they exist, the lymph-hearts. In addition, 

 there are still other special effects of the nerves upon the absorptive 

 activity of the lymphatic radicles. Kiihne noted, after irritation of the 

 corneal nerves, that the corneal cells contracted within their secretory 

 canaliculi. The following observation by Goltz is also interesting in this 

 connection. When this investigator injected a dilute solution of sodium 

 chlorid subcutaneously into the lymph-spaces, he saw that it was rapidly 

 absorbed; it remained unabsorbed, however, after destruction of the 

 central nervous system. Division of the nerves to the extremities also 

 resulted, temporarily, in retarding the absorption. 



If inflammation was excited in both posterior extremities of a dog, marked 

 edema, together with acceleration of the lymph-stream, appeared in the one in 

 which the sciatic nerve had been divided. 



If the thigh of a frog is tightly constricted until the circulation ceases, the 

 nerve being preserved, and the part is immersed in water, it becomes greatly 

 swollen (the dead thigh does not swell) ; whence it follows that absorption takes 

 place independently of the existence of the circulation. Division of the sciatic 

 nerve or crushing of the spinal cord (though not mere transverse section or separa- 

 tion of the brain) abolishes absorption. 



ABSORPTION OF PARENCHYMATOUS EFFUSIONS. 



Fluids that transude into the tissue-spaces from the blood-vessels, or those 

 that are injected into the parenchyma through a needle, undergo absorption. 

 In this process the blood-vessels participate primarily, and the lymphatics also 

 secondarily. Into the latter, there pass from the clefts and secretory spaces in 

 the connective tissue, even small particles, as, for example, granules of cinnabar 

 and India ink after tattooing of the skin, blood-corpuscles from hemorrhagic 

 extravasations and fat-droplets from the marrow of fractured bones. If all the 

 lymphatics of a part be ligated, absorption still takes place just as rapidly as 

 before. Therefore, the absorbed fluid must have passed through the delicate 

 membranes of the blood-vessels. The opposite observation, that no absorption 

 of parenchymatous fluids takes place after ligation of all the blood-vessels, does 

 not exclude a participation of the lymphatics in the process. of absorption, because, 

 after ligation of all of the blood-vessels, naturally all formation of lymph in the 

 tissues, and consequently any lymph-current, must cease. The absorption of 

 fluids introduced into the tissues artificially, particularly in the subcutaneous cellular 

 tissue (parenchymatous and subcutaneous injection), generally takes place 

 rapidly, as a rule more rapidly than after administration by the mouth. There- 

 fore, subcutaneous injections of drugs in solution are much employed for thera- 

 peutic purposes. Naturally the substances to be injected should not have a 

 destructive, corrosive or coagulating effect upon living tissues. In addition to 

 the great rapidity of absorption, subcutaneous injection has the further advantage 

 over the administration of a drug by the mouth that some agents that are ingested 

 undergo decomposition in the stomach and intestine as a result of the digestive 



