THEORIES OF IMMUNITY. 



ently shown that a mixture of antitoxine and 

 toxine neutral to one species of animal was not 

 neutral to another; if this was so, there could have 

 been no chemical union between the two. These 

 experiments are discredited, however, by the sup- 

 porters of the chemical theory of union, on the 

 ground that the mixture was not exactly neutral 

 in the first place. 



Apparently the strongest support of the 

 theory of chemical union are the experiments 

 of Martin and Cherry (Proc. Royal Soc. of 

 London — quoted by Ritchie, I.e.), mentioned 

 above, in which they tested the behavior of 

 mixtures of toxine and antitoxine when passed 

 through a porcelain filter whose pores had been 

 filled with gelatine. The non-appearance of the 

 toxine after a time they interpret as an indica- 

 tion that a complete chemical union had taken 

 place — although the opponents of the theory 

 of chemical action say that the results may be 

 equally dependent upon an actual degeneration 

 of the toxine due to the amount of time elaps- 

 ing, such as is constantly seen when toxine is 

 allowed to stand by itself. 



54 



