PART PLAYED BY FERMENTS. 159 



The two diseases in which there is most evidence of a 

 ferment action are diphtheria and tetanus. Apart from the 

 fact that a digestive action has occurred, which the presence 

 of albumoses in the body of an animal dead of these 

 diseases affords, the chief available evidence for the exist- 

 ence of ferments lies in this, that the toxic products of 

 the bacteria involved lose their toxicity by exposure to a 

 temperature which puts an end to the diastatic activity of 

 such an undoubted ferment as that of the gastric juice. If 

 a bouillon containing diphtheria toxine be heated at 65 C. 

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

 effect. There is evidence, however, that there remains a 

 substance unaffected by the heat which, as we shall see 

 later, is also toxic. In the case of B. tetani growing in 

 artificial media similarly treated, all the toxicity is lost by 

 exposure at 65 C. Both in this disease and in diphtheria 

 there is a still further fact which is adduced in favour of 

 a ferment being concerned in the toxic action, namely, the 

 existence of a definite period of incubation between the 

 injection of the toxic bodies and the appearance of 

 symptoms. This may be interpreted as showing that after 

 the introduction of say a filtered bouillon culture, further 

 chemical changes have to be set up in the body before the 

 actual toxic effect is produced. In the pharmacological 

 action of some simple chemical bodies, however, there is 

 observed a delay in the appearance of symptoms, and 

 with some poisons presently to be mentioned which are 

 closely allied to the bacterial toxines an incubation period 

 may not exist. Thus the toxic action of bacteria may 

 be a very complicated process, and the initial elaboration 

 of a ferment may occur. Such a ferment injected into 

 an animal might give rise, by a process of digestion, to 

 toxic substances of a non-diastatic nature. The injection 

 of the latter, derived from previous digestive action outside 

 an animal's body, might also give rise to toxic effects. 

 Our knowledge of the subject is at present, however, too 

 scanty for a definite opinion to be expressed as to whether 

 ferments play a part in the action of pathogenic bacteria or not. 



