368 THE LYMPHATIC SYSTEM. 



is more or less colorless and transparent, or whitish and opaque, accord- 

 ing to the proportion of fatty matter present in the specimen. After 

 coagulation, it separates into a liquid serum and a solid clot, precisely 

 as in the case of blood. 



It thus appears that both fibrine and albumen are either formed in the 

 interior of the lymphatic system, or transude to a certain extent from 

 the bloodvessels, even in the ordinary condition of the circulation. If 

 so, this transudation takes place in so small quantity that the albumi- 

 nous matters are all taken up by the lymphatic vessels, and do not 

 appear in the excreted fluids. 



When lymph is drawn from the thoracic duct and allowed to coagu- 

 late, the clot after a few moments almost invariably assumes a decided 

 pink color, and on microscopic examination is found to contain a very 

 few red blood-globules. The presence of these globules is attributed by 

 some competent authorities (Kolliker, Robin) to the accidental rupture 

 of capillary bloodvessels and consequent introduction of their contents 

 into the lymphatic system ; but their occurrence is so constant that it 

 must be doubted whether they have altogether an accidental origin. 

 The pinkish color of the lymph under these circumstances is never per- 

 ceptible when it is first drawn from the vessels, but only after it has 

 been for a short time exposed to the air. 



An important peculiarity in regard to the fluid of the lymphatic 

 system, especially in the carnivorous animals, is that it varies, both in 

 appearance and constitution, at different times. In the ruminating and 

 graminivorous animals, as the sheep, ox, goat, and horse, it is either 

 opalescent with a slight amber tinge, or nearly transparent and color- 

 less. In the carnivorous animals, as the dog and cat, it is also opaline 

 and amber colored in the intervals of digestion, but soon after feeding 

 becomes of a dense, opaque, milky white, and continues to present that 

 appearance until digestion and absorption are complete. It then regains 

 its original aspect, and remains opaline until digestion is again in pro- 

 gress. 



The results of analysis show that this variation in the appearance of 

 the fluid of the thoracic duct during digestion, like that of the blood, is 

 due to the absorption of fatty matters from the intestine. Although 

 the chyle is richer than lymph in nearly all its solid ingredients, the 

 principal difference between the two consists in the proportion of fat, 

 which is nearly absent from the transparent or opaline lymph, but very 

 abundant in the white and opaque chyle. This is shown in the following 

 analysis by Dr. Rees, 1 of lymph and chyle from the ass. 



1 In Colin, Physiologic compare des Animaux domestique. Paris, 1856 tome 

 ii. p. 18. 



