(EDEMA AND DROPSY. 419 



cyanic acid is not formed, as the emulsin seems to be destroyed in the alimentary 

 canal. If the emulsin, however, be injected into the blood, and the amygdalin 

 be given by the mouth, the animal is rapidly poisoned, owing to the formation 

 of hydrocyanic acid, as the amygdalin is rapidly absorbed from the intestinal 

 canal. The amygdalin, a glucoside (CgoH^NOn), is acted upon by fresh 

 emulsin like a ferment ; it takes up 2 (H 2 O) and yields hydrocyanic acid (C H N), 

 -f-oil of bitter almonds (C 7 H 6 0), + sugar 2 (C 6 H 12 6 ) (Cl. Bernard). 



When serum is injected subcutaneously, it is rapidly absorbed; it is decomposed 

 within the blood-stream, and increases the amount of urea (p. 62, 2). Albuminous 

 solutions, oil, peptones and sugars are also absorbed (Eichhorst). 



203. Congestion of Lymph and Serous Effusions. 



(Edema and Dropsy. 



[As aptly illustrated by Lauder Brunton, the lymph-spaces may be represented 

 by cisterns, each of which is provided with .supply pipes the arteries and 

 capillaries; while there are two exit pipes the veins and lymphatics. In health, 

 the balance between the inflow and outflow is such, that the spaces are merely 

 moistened with fluid. When a cannula is placed in a lymphatic vessel in a dog, 

 only a few drops of lymph flow out at long intervals. Emminghaus found that, if 

 the veins of the limb be ligatured, the lymph flows much more quickly. This is 

 in part due to the increased transudation of fluid from the small blood-vessels, but 

 as Brunton suggests, it may also be due to fluid passing away by the lymphatics 

 when it can 110 longer be carried away by the veins. We cannot say what is the 

 relative share of the veins and lymphatics, nor in the above experiment do we 

 know how much is due to increased transudation or diminished absorption. 

 When there is an undue accumulation of fluid in the lymph-spaces, we have the 

 condition termed dropsy.'} 



If the efferent veins and lymphatics of an oi'gan be ligatured, or if resistance be 

 offered to the outflow of their contents, congestion and a copious transudation of 

 lymph into the tissues take place. These are most marked in the skin and sub- 

 cutaneous cellular tissue. The soft parts swell up, without pain or redness, and a 

 doughy swelling, which pits on pressure with the finger, results. These are the 

 signs of lymph-congestion, which is called (edema when the fluid is watery. 



Under similar circumstances, lymph is effused into the serous cavities. If at the 

 same time, a large number of colourless blood-corpuscles pass out of the blood- 

 vessels into the cavity, the fluid becomes more and more like pus. In order that 

 these corpuscles may proliferate, a considerable percentage of albumin is neces- 

 sary. When the pressure within the serous cavity rises above that in the small 

 blood-vessels, water may pass into the blood. These sero-puruleiit effusions not 

 unfrequeutly undergo changes, and yield decomposition products, such as leucin, 

 tyrosin, xanthin, kreatin, kreatinin (?), uric acid (?), urea. Endothelium from the 

 serous cavity (Quiucke), sugar in pleuritic effusions (Eichhorst), and in cedemas 

 with little albumin (Rosenbach), cholesterin frequently in hydrocele fluid, and 

 succinic acid in the fluid of echinococci have all been found in these effusions. 



The effusion of lymph may arise not only from pressure upon the lymphatics, 

 but also from inflammation and thrombosis of the lymphatics themselves, in which 

 cases not unf requently new lymphatics are formed, so that the communication is 

 re-established. Sometimes the ductus thoracicus bursts and lymph is poured 

 directly into the abdomen or thorax. [Ligature of the thoracic duct results in 

 rupture of the receptaculum chyli and escape of chyle and lymph into the large 

 serous cavities (Ludwig).] 



When dropsy or effusion of fluids occurs into serous cavities, there is always a 



