BLOOD, LYMPH, AND CHYLE 151 



blood through the walls of the vessels into the spaces 

 between those walls and the substance of the tissues 

 around. This fluid is called lymph, and is that which 

 nourishes the tissue elements. It is clear, nearly trans- 

 parent, and contains more water with less solid matter 

 than the plasma of the blood. White corpuscles similar 

 to those in the blood are found in it, and, like the blood, 

 it coagulates by the formation of fibrin. Like the blood, 

 also, lymph is conveyed from the tissues in tubes, the 

 lymphatics or lymphatic vessels, which finally join the great 

 blood vessels, and so return to the blood the substances 

 drawn from it in the capillaries. 



210. Lacteals and Chyle. The lymphatics of the small 

 intestine are called lacteals ; after a meal containing fat, 

 they convey, instead of clear lymph, a milky fluid which 

 is called chyle, and is a product of digestion. 



EXPERIMENTS 



72. Blood Corpuscles. Prick the finger with a sterilized needle, 

 mount the drop of blood thus obtained, and examine it with both low 

 and high powers of the compound microscope. There will be seen 

 large numbers of round bodies of a faint red tint the red cor- 

 puscles. These are seen to be small disks, and appear dumb-bell 

 shaped when viewed on edge, owing to their being thinner in the 

 center than on the edges. Occasionally among the red corpuscles 

 may be seen slightly larger, transparent, sometimes irregular, bodies 

 the white or colorless corpuscles. If watched for some time, they will 

 probably show slight changes in shape. 



73. Clotting of Blood. At a slaughterhouse fresh blood can be 

 obtained. If it be stirred vigorously immediately after being drawn 

 from the blood vessels, the fibrin can be separated from the blood 

 serum and corpuscles. Blood allowed to stand after being drawn 

 shows a firm clot. Both "whipped" blood and fibrin and the clotted 

 blood should be examined by the pupils. 



The clotting of blood may be prevented by adding to it, as it is 



