MODE OF PRODUCTION OF ANTITOXINES. 477 



little effect, Ransom has found neutralising capacity almost 

 entirely absent. A definite theory, in accordance with 

 these and other facts, has been formulated by Ehrlich. He 

 supposes that there normally exist in the cells of an animal 

 capable of supplying antitoxine certain atom-groups which, 

 while ordinarily performing a physiological function, are 

 also capable of combining with the toxine molecule. Thus, 

 for example, when diphtheria toxine is injected into a horse 

 in relatively small doses the toxine combines with these 

 atom groups and their function in the cell economy is lost. 

 There then occurs a regeneration of new molecules to take 

 up this function, and when these are again used up by 

 fresh toxine molecules introduced a further regeneration 

 takes place. Ultimately there occurs an over-regeneration, 

 and the appearance of these molecules (antitoxine) in the 

 blood. It is to be noted that when the symptoms of 

 poisoning occur, in tetanus for example, these combining 

 molecules do not act as antitoxines, but constitute the 

 means by which the toxine is bound to the nerve cell, and 

 thus produces its effects. It is only when they are freed 

 from their attachment to the cell protoplasm that they act 

 as antitoxines. 



Whilst this theory cannot be regarded as completely 

 established, we may state that it seems to us to be in 

 harmony with the conditions affecting the rapid and suc- 

 cessful production of antitoxines. It also explains why 

 modified toxines, e.g., tetanus toxine treated with carbon 

 bisulphide, may be efficient immunising agents. It need 

 scarcely be pointed out that the direct proof of combination 

 of tetanus poison with nerve cells, as mentioned above, is 

 another argument in its favour. Two other facts of im- 

 portance may be mentioned. The first is that an animal, 

 after having been successfully treated with toxine, may 

 supply an amount of antitoxine much greater than the total 

 quantity of toxine employed in the process the quantity 

 of each being reckoned by thek neutralisation value. The 

 second is that after a horse with antitoxic serum has been bled, 

 the antitoxic value of its serum, which of course falls at first, 



