BLOOD AND LYMPH 263 



gogues. Such substances . as sugar, urea, certain salts (especially 

 sodium chloride), peptone, egg albumin, extracts of dogs' liver and 

 intestine, crab muscles and blood leeches are included in this class. 



In a fasting animal, the lymph coming from the intestine is a clear, 

 transparent fluid possessing the characteristics already outlined. After 

 a meal containing fat has been ingested, this intestinal lymph is white 

 or " milky." This is termed chyle and is essentially lymph possessing an 

 abnormally high (5-15 per cent) content of emulsified fat. This chyle 

 is absorbed by the lacteals of the intestine and transported to the lower 

 portion of the thoracic duct. Apart from the fat value, the composition 

 of lymph and chyle are similar. 



EXPERIMENTS ON BLOOD 

 I. Defibrinated Ox-blood " 



1. Reaction. Moisten red and blue litmus papers with 10 per cent sodium 

 chloride solution and test the reaction of the defibrinated blood. Test by Congo 

 red paper also. 



2. Microscopical Examination. Examine a drop of defibrinated blood under 

 the microscope. Compare the objects you observe with Plate IV, opposite page 

 252. Repeat the test with a drop of your own blood. 



3. Specific Gravity. Determine the specific gravity of defibrinated blood 

 by means of an ordinary specific gravity swindle. Compare this result with 

 the specific gravity as determined by Hammerschlag's method in the next 

 experiment. 



4. Specific Gravity by Hammerschlag's Method. Fill an ordinary urinom- 

 eter cylinder about one-half full of a mixture of chloroform and benzene, having 

 a specific gravity of approximately 1.050. Into this mixture allow a drop of the 

 blood under examination to fall from a pipette or directly from the finger in case 

 fresh blood is being examined. Care must be taken not to use too large a drop 

 of blood and to keep the drop from coming into contact with the walls of the cyl- 

 inder. If the blood drop sinks to the bottom of the vessel, thus shdwing it to be 

 of higher specific gravity than the surrounding fluid, add chloroform until the 

 blood drop remains suspended in the mixture. Stir carefully with a glass rod 

 after adding the chloroform. If the blood drop rises to the surface upon being 

 introduced into the mixture, thus showing it to be of lower specific gravity than the 

 surrounding fluid, add benzene until the blood drop remains suspended in the 

 mixture. Stir with a glass rod after the benzene is added. After the blood 

 drop has been brought to a suspended position in the mixture by means of one or 

 more additions of chloroform and benzene this final mixture should be filtered 

 through muslin and its specific gravity accurately determined. What is the 

 specific gravity of the blood under examination? 



5. Tests for Various Constituents. Place 10 c.c. of defibrinated blood in an 

 evaporating dish, dilute with 50 c.c. of water and heat to boiling. Is there any 

 coagulation, and if so what bodies form the coagulum? At the boiling-point 

 add about 50 c.c. of very dilute acetic acid (made by adding 2 drops of 36 per cent 

 acetic acid to 50 c.c. of water) and again heat to boiling for a few moments. 



