310 GENERAL MICROBIOLOGY 



thoracic wall, in the region of the apex of the heart, shave 

 and clean with alcohol. 



(c) Insert a sterile needle attached to a sterile 20 c.c. 

 syringe, through the thoracic wall into the heart and slowly 

 draw the plunger out. 



If only a small quantity of serum is desired for testing, 

 the animal may be saved for subsequent bleedings. 



(d) Place the blood in a sterile container, allow to 

 clot and draw off the serum for standardization. 



REFERENCES 



MARSHALL: Microbiology (1911), pp. 480-484. 



BESSON: Practical Bacteriology, Microbiology and Serum Therapy 



(1913), pp. 544-548. 

 KOLMER: Infection, Immunity and Specific Therapy (1915), pp. 234, 



242, 719-729. 

 ZINSSER: Infection and Resistance (1914), p. 463. 



EXERCISE 8. A DEMONSTRATION OF THE AGGLU- 

 TINATION TEST 



Note. There are two methods of applying the agglutination 

 test: First, by combining the suspect's serum in varying amounts 

 with a suspension of the specific organism and incubating eighteen to 

 thirty-six hours; the results are then read with the unaided eye. 

 Second, the serum may be combined in varying dilutions with a sus- 

 pension of the specific organism, and hanging drop preparations made 

 and examined microscopically. If agglutinins are present, clumping 

 of the organisms will occur in a few minutes. With either method, 

 controls, containing the organism but normal serum, should be pre- 

 pared for comparative purposes. 



Apparatus. Four agar slants; test-tube rack for small 

 test tubes; twelve small test tubes; antiserum; physio- 

 logical salt solution; 1 c.c. pipettes, graduated to 0.01 c.c.; 

 5 c.c. pipettes; cover-glasses; concave slide. 



Culture. B. typhosus or B. cholerce suis. 



Method. Macroscopic Test. 1. Antigen. This is a 

 suspension of the specific organism obtained from a twenty- 

 four to forty-eight hour agar culture in physiological salt 



