PROPERTIES AND FORMATION OF LYMPH 235 



branes. It is also possible to tap the cervical lymphatic duct which 

 drains the different structures of the head. The thoracic duct, how- 

 ever, is to be preferred, because it collects the lymph from the largest 

 ■ part of the body, namely from the posterior extremities, the abdominal 

 organs, and the entire left and lower right half of the thorax. 



As the lymph is derived from the plasma of the blood, it may justly 

 be assumed that its composition is very similar to that of the mother- 

 fluid, but since the capillary wall really serves as a filter-like barrier, 

 the plasma cannot pass through it as such but only in a much diluted 

 form. For this reason, lymph is often designated as diluted plasma. 

 If gathered during periods of fasting, it is as clear as water, and only 

 slightly opalescent. It exhibits a yellowish green or yellowish gray 

 hue. Its watery consistency is indicated by the fact that its specific 

 gravity varies between 1.016 and 1.023, and its viscosity between 

 2400 and 3000. It is, therefore, only 1.7 times more viscous than 

 distilled water at 37° C.^ It possesses a salty taste, a faint odor, and 

 an alkaline reaction, equaling 0.15-0.22 per cent. Na2C03. Soon 

 after it leaves the duct, it changes into a homogeneous jelly and later 

 on into a soft coagulum which embraces large numbers of white blood 

 corpuscles of the type of the lymphocytes. These cells seem to be the 

 carriers of the clotting agent, because their number bears a close 

 relationship to the mass of the fibrin formed. The coagulation- time 

 of lymph varies between 2.5 and 7 minutes, the average time being 

 4.5 minutes. It cannot be said, therefore, that it clots less speedily 

 than blood (dog). 



Lymph contains 3.6 to 5.7 per cent, of solids, the proteins consisting of fibrin- 

 ogen, paraglobulin, and serum-albumin. When derived from the lymphatics of 

 the liver, it presents an especially high percentage of albumin. Its fat content is 

 small, namely 0.06 per cent. The salts comprise principally sodium chlorid and 

 sodium carbonate. Diastatic and lipolytic ferments are also present. The 

 following analytical data have been furnished by Munk. 



Water 94 . 38-96 . 53 per cent." 



Solids 3 . 66- 5 . 62 per cent. 



Albumin : 3 . 52- 3 . 54 per cent. 



Reducing substances . 09- . 10 per cent. 



Minerals 



NaCl 0. 583 gram in 100 c.c. 



NazCOa 0.217 gram in 100 c.c. 



K2HPO4 0.028 gram in 100 c.c. 



Ca3(P04)2 0.028 gram in 100 c.c. 



MgsCPOOa 0.009 gram in 100 c.c. 



Fe3(P04)2 0. 0025 gram in 100 c.c. 



0.87 per cent. 



If the animal is fed with food containing fat, the lymph traversing 

 the thoracic duct eventually assumes a milky appearance. It is then 

 known as chyle. This change becomes noticeable about 2 to 3 hours 

 after the ingestion of this particular kind of food and is attributable 

 to the absorption of globules of fat which gain the lymphatic system 

 through its intestinal radicles, commonly designated as lacteals. By 



^ Burton-Opitz and Nemser, Am. Jour, of Physiol., xlv, 1917, 25. 



