BLOOD AND LYMPH 265 



microscope (see Figs. 83 and 156, pages 264 and 490). What do you find and 

 what is your explanation from the standpoint of osmotic pressure? 



9. Hemagglutination. The common garden bean, such as the 

 Scarlet Runner, 1 contains a protein substance which exhibits the 

 interesting property of causing a clumping or agglutination of red 

 blood corpuscles. 2 



Dilute defibrinated blood 3 ten times with physiological sodium chloride solu- 

 tion (0.9 per cent) and place i c.c. in each of three small test-tubes. 



Grind three beans in a coffee mill, or with mortar and pestle to a fine meal 

 and extract for a few minutes with 0.9 per cent sodium chloride solution. Filter 

 and add 0.05 c.c. (about 2-3 drops) of the filtered extract to the first of the blood 

 tubes ; o.oi c.c. to the second ; and 0.05 c.c. of 0.9 per cent sodium chloride to 

 the third. 



Invert each tube to mix the contents thoroughly, and note the rapid agglutina- 

 tion and precipitation of the blood corpuscles hi the first tube, a less rapid agglu- 

 tination in the second, while the third or control tube remains unaltered. In 

 one-half hour the corpuscles hi the first tube often are packed solid and one is 

 able to pour off perfectly clear serum. 



If the remainder of the bean extract is boiled for a few minutes, the coagulum 

 filtered out and 0.05 c.c. of the filtrate added to the control tube, still no agglutina- 

 tion occurs, indicating that the hemagglutinin has been destroyed or removed 

 by the boiling. 



10. Diffusion of Hemoglobin. Prepare some hemolyzed ("laky") blood, 

 thus liberating the hemoglobin from the erythrocytes. Test the diffusion of the 

 hemoglobin by preparing a dialyzer like one of the models shown in Fig. 2, page 

 24. How does hemoglobin differ from other well-known crystallizable bodies? 



11. Guaiac Test. By means of a pipette drop an alcoholic solution of guaiac 

 (strength about i :6o) 4 or the Lyle-Curtman guaiac reagent 5 (see p. 237) into 

 the solution under examination 6 until a turbidity is observed and add old tur- 

 pentine or hydrogen peroxide, drop by drop-, until a blue color is obtained. 



In the detection of small amounts of blood the quantity of guaiac 

 used should also be decreased. Do any other substances respond in a 

 similar manner to this test? Is a positive guaiac test a sure indication 

 of the presence of blood? (See discussion on page 261.) 



1 The Scarlet Runner is a familiar variety purchasable in every seed store. It occurs in 

 two varieties, the white and the red. Ricin, a protein constituent of the castor bean, also 

 possesses pronounced agglutinating properties. Because of its poisonous nature it is, how- 

 ever, not suitable for use in class experiments. 



2 Mendel: Archimo di fisiologia, 7, 168, 1909; Schneider: Journal Biol. Chem., 11,47, 

 1912. 



3 Rabbit's blood is especially desirable (Mendel: loc. cit.} and may be obtained for the 

 purpose by bleeding from a small cut on the animal's ear and defibrinating, 



4 Buckmaster advises the use of an alcoholic solution of guaiaconic acid instead of an 

 alcoholic solution of guaiac resin. 



5 Lyle and Curtman; Jour. Biol. Chem., 33, i, 1918. 



6 Alkaline solutions should be made slightly acid with acetic acid, as the blue end- 

 reaction is very sensitive to alkali. 



