THE BLOOD AND THE LYMPH 



275 



lungs, the lungs within the chest-walls, the diaphragm over the abdominal 

 contents, the abdominal viscera on each other, the bones in the joints, 

 etc., much friction would be caused were the intervening surfaces not 

 well lubricated. Indeed, we cannot see how these organic movements 

 could go on without this liquid supplied in just the right amounts between 

 these opposed surfaces. In pleurisy, for example, a slight roughness is 

 sometimes produced by the inflammatory exudation of fibrin on the 

 pleura, and the accompanying pain and disturbance of function are severe. 

 The lubricant of all these surfaces is lymph, and it is sometimes said 

 that lymph "takes its origin" in part from the serous sacs. It does so 

 in a certain sense, but it is better to consider that it lubricates these 



FIG. 144 



FIG. 145 



The structure of the peritoneum: a, flat The root of the aorta from in front, the valve 



endothelial cells; 6, stoma. A lining with being shut: 1, right; 2, left; and 3, posterior 

 such a structure is obviously ideally adapted semilunar valve-flaps; 4, ascending aorta; 5 

 to be a lubricating surface between the ever- and 6, left and right coronaries, respectively, 

 moving abdominal viscera. Another func- (Rauber.) 

 tion of the peritoneum is to shut off local 

 inflammations, e. g., appendicitis, from the 

 fatal involvement of the whole abdominal 

 cavity. (Bates.) 



surfaces and then osmoses and drains away in the lymphatic vessels, the 

 membranes constantly " secreting" their necessary supply from their 

 blood-capillaries. 



When almost any reasonable amount of harmless liquid (for example 

 0.06 per cent, aqueous solution of sodium chloride) is injected into the 

 blood-vessels, it is very soon transuded into the lymph-spaces and into 

 the gut and the blood has thereupon resumed its normal specific gravity. 

 Thus, in surgical shock, where there is a dangerously low blood-pressure 

 preventing metabolic exchange between circulation and tissues, the 

 injection of Ringer's solution or of "normal saline" into the blood raises 

 its pressure for only a few minutes, owing to this rapid transudation; 

 the infusion soon has to be repeated. In respects other than that of 



