342 THE LYMPH. 



Why this is we do not know, but it has been suggested that each 

 fat droplet is surrounded by a delicate albuminous envelope, which 

 is derived from the normal albumins of the lymph. On the other 

 hand, it is conceivable that the surface layer of each droplet con- 

 sists of modified fat or of a denser layer of the fluid in which it is 

 suspended. 



The fats which are found in the lymph are always identical with 

 those of the food, and can be recovered for analytical purposes by 

 extracting with ether. In its course through tissues which are rich 

 in fat no fat is absorbed. 



Soaps are present in the lymph in only very small amounts. 



The albumins which are found in the lymph are the same as those 

 of the blood, and are present in the same ratio to each other. The 

 amount varies somewhat with the character of the lymph, but is 

 normally always smaller than that of the blood-plasma. Like the 

 blood-plasma, so also does the lymph coagulate on standing. The 

 coagula, however, are very delicate and tend to separate out in frac- 

 tions. Some tran sudates, indeed, such as pericardial effusions and 

 hydrocele fluid, do not coagulate spontaneously at all, while coagula- 

 tion occurs at once if leucocytes or blood is added. The peculiar 

 behavior of such lymph is no doubt due to the absence of cellular 

 elements. It is to be noted also that following the injection of 

 those substances which prevent coagulation of the blood coagula- 

 tion of the lymph similarly does not occur. 



Other albumins besides serum-albumin, serum -globulin, and fibrin- 

 ogen are not found in normal lymph, such as we obtain from the 

 thoracic duct, for example. Under pathological conditions, how- 

 ever, the exudates more particularly may contain the various albu- 

 minous derivatives of the leucocytes, such as nucleins, nucleo- 

 albumins, etc. In cysts of the ovaries and their appendages met- 

 albumin or paralbumin may further be found. 



The amount of sugar which is found in normal lymph is fairly 

 constant, and is derived from the hepatic lymph. It can be increased 

 artificially by ligating the ureters and then injecting glucose into 

 the blood. It is noteworthy that under such conditions the lymph 

 may contain a larger percentage of sugar than the blood itself. This 

 further shows that the formation of lymph cannot be explained 

 upon the basis of filtration and osmosis only, and demonstrates 

 the specific activity of the endothelial lining of the capillaries. 

 Under pathological conditions, it is claimed, sugar may be altogether 

 absent. 



The extractives of the lymph are essentially the same as those of 

 the plasma. In certain districts, however, the one or the other will 

 be found to preponderate, and in some localities we further meet 

 with extractives which are peculiar to that particular region. In 

 the cerebrospinal fluid, for example, pyrocateehin has been found ; 

 allantoin is present in the allantoic fluid and in ascitic accumula- 

 tions ; succinic acid and inosit may be obtained from hydrocele 



