168 THE TOXINS PRODUCED BY BACTERIA 



digestion, has raised the question of the possibility of the elabora- 

 tion by these bacteria of ferments by which the process may be 

 started. Thus Sidney Martin puts forward the view that 

 ferments may be produced, which we may look on as the 

 primary toxic agents, and which act by digesting surrounding 

 material and producing albumoses, these poisons being, as it 

 were, secondary poisons. Hitherto all attempts at the isolation 

 of bacterial ferments of such a nature have failed. 



But apart from the fact that with such bacteria as these of 

 tetanus and diphtheria, a digestive action may occur, analogies have 

 been drawn between ferment and toxic action. The chief facts 

 upon which such analogies have been founded are as follows. 

 Thus the toxic products of these and other bacteria lose their 

 toxicity by exposure to a temperature which puts an end to the 

 activity of such an undoubted ferment as that of the gastric 

 juice. If a bouillon containing diphtheria toxin be heated at 

 65 C. for one hour, it is found to have lost much of its toxic 

 effect, and in the case of b. tetani all the toxicity is lost by 

 exposure at this temperature. In both diseases there is a still 

 further fact which is adduced in favour of the toxic substances 

 being of the nature of ferments, namely, the existence of a 

 definite period of incubation between the injection of the toxic 

 bodies and the appearance of symptoms. This may be inter- 

 preted as showing that after the introduction of, say, a filtered 

 bouillon culture, further chemical substances are formed in the 

 body before the actual toxic effect is produced. Too much 

 reliance must not be placed on such an argument, for in the 

 case of tetanus, at least, the delay may be explained by the fact 

 that the poison apparently has to travel up the nerve trunks 

 before the real poisonous action is developed. Further, with 

 some poisons presently to be mentioned which are closely allied 

 to the bacterial toxins an incubation period may not exist. 

 It would not be prudent to dogmatise as to whether the toxins 

 do or do not belong to such an ill-defined group of substances 

 as the ferments. It may be pointed out, however, that the 

 essential concept of a ferment is that of a body which can 

 originate change without itself being changed, and no evidence 

 has been adduced that toxins fulfil this condition. Another 

 property of ferments is that so long as the products of fermenta- 

 tion are removed, the action of a given amount of ferment is 

 indefinite. Again, in the case of toxins no evidence of such an 

 occurrence has been found. A certain amount of a toxin is 

 always associated with a given amount of disease effect, though 

 a process of elimination of waste products must be all the time 



