196 THE TOXINS PRODUCED BY BACTERIA 



bodies whose toxophorous atom groups have become degenerated, 

 Ehrlich gave the name toxoids. The theory may afford an ex- 

 planation of what has been suspected, namely, that in some 

 instances toxins derived from different sources may be related 

 to one another. For example, Ehrlich pointed out that ricin 

 produces in a susceptible animal body an antitoxin which 

 corresponds almost completely with that produced by another 

 vegetable poison, robin (vide supra). This may be explained 

 on the supposition that robin is a toxoid of ricin, i.e., their 

 haptophorous groups correspond, while their toxophorous differ. 

 The evidence on which Ehrlich's deductions were based is of 

 a very weighty character, but another view of toxic action is 

 that the relation between a toxin and the cell on which it acts 

 is an example of the physical phenomenon of adsorption. The 

 whole subject will be again referred to in the chapter on 

 Immunity. 



With regard to the intracellular toxins we shall see it is 

 difficult to determine whether or not they share with the extra- 

 cellular poisons the property of stimulating antitoxin formation, 

 — if they do not, then they may belong to an entirely different 

 class of substances. It is certain that immunity against such 

 poisons is difficult to establish and is not of a lasting dharacter. 

 We thus cannot say what the mechanism is by which these 

 poisons act. It may be said that Macfadyen, by grinding up 

 typhoid bacilli frozen by liquid air, claimed that on thawing he 

 obtained the endotoxins in liquid form, and he further stated 

 that by using this fluid he could immunise animals not only 

 against the toxins but also against the living bacteria. 



We have already pointed out that those who claim for the 

 aggressins a special character hold that the activity of these 

 bodies has as its effect the interference with the phagocytic 

 functions of the leucocytes. They also hold that a special type 

 of immunity can be developed against the aggressins. 



