62 IMMUNITY 



The tubes receive first the solutions on the left and are placed 

 in the 37 C. incubator for 2 hours to allow union of their various 

 parts, particularly the complement with others. They then receive 

 the solutions on the right, are placed in the incubator for half an 

 hour and in the ice-box overnight, when they are examined for a 

 .solution of the red coloring matter. If it occurs, the column is 

 perfectly clear red with some residue of extracted cells. If no 

 hemolysis has occurred, the red cells form a layer at the bottom, 

 and the column is clear and colorless. 



A and B are the tests of syphilitic sera while the remaining are 

 to find out if the other solutions affect the results of A and B. Of 

 course tube G represents simply the complete hemolytic system. 

 The extra tests are to exclude the possibility of interference on the 

 part of any single member with the complement No. 4. The 

 character of the test is found in tube A where syphilitic antigen and 

 serum have bound or fixed the complement so that it cannot unite with 

 the rabbit serum and sheep's corpuscles to hemolyze the latter. This is 

 a positive test. A negative test is when hemolysis occurs, since no anti- 

 body is present to unite with complement in the presence of antigen. 



Complement Deviation. This is a condition arising when 

 there is too much amboceptor and too little complement. The 

 free amboceptors adsorb complement and there is none left for cell 

 needs or renewed demands. It is to be distinguished from com- 

 plement fixation. The terms are not interchangeable. 



Cholera and typhoid organisms do not produce soluble toxins in 

 the body, but when they are disintegrated therein, soluble poisons 

 (intracellular) are liberated. 



Bacteria may become accustomed to the fluids of the body by a 

 similar process and may elaborate free receptors for their own pro- 

 tection, i.e., anti-bacteriolysins. (Welch's theory.) 



In the aged, and in chronic disease of the liver and kidneys, the 

 complement existing in the blood may become reduced in quantity, 

 and the individual may succumb to an infection, which ordinarily 

 would be mild. 



