280 A MANUAL OF VETERINARY PHYSIOLOGY 



food. It consists of a mass of adenoid tissue, the network of 

 which is filled with leucocytes ; within the network are capillary 

 bloodvessels, and surrounding the whole is a space across which 

 branches of the adenoid network pass. This space is known as a 

 lymph space or sinus ; it is lined, like those previously described, 

 with epithelioid plates, and opens into a lymphatic vessel. As 

 the lymph passes through the adenoid tissue, some of the cor- 

 puscles found in the meshes of the network are added to it, and 

 become lymph corpuscles. 



Chyle is a turbid fluid of alkaline reaction and a specific 

 gravity of 1007 to 1022. In starving animals it is transparent 

 owing to the absence of fat, and it is, in fact, at this time prac- 

 tically pure lymph. Colin observed that the chyle of herbivora 

 was yellowish or yellowish-green ; it is possible that this colour 

 may be due to chlorophyll taken up from the food. In the horse, 

 as collected from the thoracic duct, it is often blood-stained, 

 due, as we have seen, to leakage from the vena cava. 



In the small intestines of the horse it has been observed by 

 Colin that almost immediately after food has been given waves 

 of chyme are passed into the duodenum from the stomach ; in 

 consequence, the lacteals in the mesentery in connection with 

 this portion of intestine become opaque, though previously they 

 were filled with a colourless fluid. As the chyme passes along 

 the bowel the other lacteals in their turn become opaque, until 

 at last the whole of them are filled with this milky fluid. Colin 

 draws especial attention to this regular invasion of the lacteals 

 from the duodenum to the ileum. 



The movement of chyle is due to the rhythmical muscular 

 contractions of the walls of the intestine, and to the muscular 

 contraction of the intestinal villi forcing it onwards, while the 

 valves in the lacteals prevent its return. Its subsequent passage 

 into the general circulation has already been traced. 



