236 MEDICAL BACTERIOLOGY 



By varying and extending these experiments it can be demonstrated that 

 complement is present in the blood serum of all warm-blooded animals through- 

 out life. The amount of complement present per cubic centimeter in the blood 

 serum is about the same in any given animal at all times. The amount of 

 complement per cubic centimeter in the serum of one animal is nearly the same 

 in all other animals of the same species, but variations do occur. The comple- 

 ment present in the serum of an animal can unite with any amboceptor present 

 in the serum of that animal or any other animal of the same species. Comple- 

 ment of identical nature is possessed by several species and is therefore capable 

 of uniting with amboceptors found in any of them. The complement present 

 in the serum of guinea-pigs, rabbits and man is practically the same, therefore, 

 guinea-pig complement can unite with amboceptors present in human serum, 

 and those in rabbit serum. Complement is at once destroyed by heating serum 

 to 55C. for % hour; it gradually leaves the serum after the serum is withdrawn 

 from an animal, even though the serum is not heated. If serum is allowed to 

 stand at room temperature it loses its complement in about 24 hours or less. 

 If serum is placed in a refrigerator immediately after taken from an animal it 

 retains its complement for from 24 to 72 hours. If serum is frozen immediately 

 after taken from an animal it retains its complement for a number of days. 



The complement-amboceptor experiments demonstrate that a given amount 

 of complement will unite with a definite amount of amboceptor and no more. 



Amboceptor is specific in action it will only attack the substance that stim- 

 ulated its production. 



Amboceptor only unites with complement in the presence of the substance 

 which stimulated the production of the amboceptor. When complement unites 

 with an amboceptor it can never leave that amboceptor to unite with another 

 amboceptor. The amount of amboceptor per cubic centimeter in the serum of 

 an animal depends upon the method of inoculation with the substance that stimu- 

 lates amboceptor production, upon the size and number of inoculations and 

 the interval between the time of inoculation and the time when serum is 

 examined. 



The amount of amboceptor per cubic centimeter in the serum of any given 

 animal varies from time to time, usually growing less as the animal ages. 



The amount of amboceptor per cubic centimeter in the serum of different 

 animals of the same species subjected to identical inoculations is subject to 

 wide variations. 



When serum containing amboceptor is taken from an animal under aseptic 

 precautions, placed in hermetically sealed containers and immediately stored in 

 a refrigerator, the amount of amboceptor per cubic centimeter will remain almost 

 constant, decreasing only a small fraction of a per cent, per month, for many 

 months. 



The addition of chloroform to serum to prevent bacterial growth has no 

 effect on its amboceptor content. Amboceptor is not affected by heating to 

 55C. for }/ hour; a temperature of about 6oC. or 7oC. will destroy it. 



