186 IMMUNITY. 



mixed with 1 c.c. of diphtheria toxin, containing ten fatal doses, in- 

 jected into a guinea-pig did not cause death, and from this they con- 

 clude that they have converted the toxin into antitoxin. They state 

 that during the electrolytic progress a peculiar odor resembhng that 

 of chlorid of lime is given off, " but it was found that the fluid con- 

 tained only one-tenth of one per cent, of chlorin." They made no 

 control experiment in order to determine whether or not this amount 

 of chlorin will destroy the quantity of diphtheria toxin employed by 

 them, and until such an experiment has been made we will be in- 

 clined to the opinion that the 5 c.c. of electrolyzed solution contained 

 enough chlorin not only to destroy its own toxin, but also that in the 

 1 c.c. of non-electrolyzed toxin with which it was mixed. 



It must be admitted that it is within the range of possibility that 

 antitoxins may contain a ferment derived from the toxin, and which 

 in the animal body during the process of immunization has com- 

 bined with the constituents of certain tissues. This view is in ac- 

 cord with the experimental observations of Emmerich and Low, 

 which we have already detailed. 



Centanni endeavored to determine experimentally what organ or 

 tissue of the body is affected in the production of immunity against 

 rabies. His work consisted in endeavoring to induce immunity in 

 a second series of rabbits by treating them subcutaneously with the 

 blood serum and with emulsions made from the various organs of the 

 members of a primary series, already rendered partially or wholly 

 immune by the ordinary method. In doing this he used amounts of 

 each tissue proportional to the weight of the animal ; thus the central 

 nervous system of an average rabbit is equal in weight to one three 

 hundredth part of the total body weight of the animal, and the total 

 blood of the same animal furnished an amount of serum equal in 

 weight to one one hundred and fiftieth part of its body weight. 

 Therefore he injected into a rabbit weighing 1,800 grams, six grams 

 of nervous tissue made into an emulsion, and into another of the same 

 weight, 12 grams of blood serum taken from rabbits already made 

 immune, and then tested the immunity of the members of this second 

 series. Emulsions of other tissues were employed in proportionately 

 the same doses. By this procedure he found, as he thinks, that in 

 the production of immunity against rabies, the immunizing substance 

 is stored up in the central nervous system. Moreover he found that 

 the immunizing substance remained in the nervous system long 

 after it had disappeared from the blood and other organs. Thus it 

 would seem that Pasteur hit upon the right thing exactly when he 

 selected emulsions of the spinal cord as the proper material with 

 which he could best induce immunity against hydrophobia. From 

 these experiments, Centanni drew the general conclusion that in the 

 production of immunity against any diseases, the immunizing sub- 

 stance is stored up in greatest quantity and most permanently in 



