CH. XI] THE ENZYME THEORY OF DISEASE 167 



passed through a Chamberland filter, a bacteria-free filtrate 

 was obtained which nevertheless retained the power of the 

 original culture to liquefy gelatin. 



16. One objection may be urged at this point, namely, 

 that it has not hitherto been possible to separate from 

 any pathogenic organism an enzyme capable of producing, 

 outside the living body, the toxins characteristic of that 

 organism. It is, however, equally impossible in many cases 

 to isolate from bacteria agents which will bring about 

 other of their functions which we recognise to depend on 

 ferment action. Moreover, we have discussed under the head 

 of virulence {vide p. 77) some of the qualities in which 

 artificial media difler from the vital fluids of the body and 

 such differences may well prove an insuperable obstacle to 

 the performance by an enzyme of its usual functions. A pick- 

 pocket may ply his "trade" vigorously in a busy crowded 

 thoroughfare and yet a few hours later, in a workhouse ward, 

 give no sign of his peculiar abilities. In the latter situation 

 certain things are lacking — the incentive which normally 

 stimulates him (that is to say, the "struggle for existence"), the 

 materials he seeks to gain, the conditions essential to his 

 work — and this fact may render difiicult if not impossible 

 any display of his customary activities. 



The enzyme theory of disease is not at the present stage 

 of our knowledge capable of proof. The above considerations, 

 however, lend some measure, if not of certainty at least of 

 probability to the supposition that the organisms associated 

 with certain diseases are not themselves the causal agents of 

 those diseases but merely act as carriers of ultra-microscopic 

 bodies, possibly parasitic in character, which have hitherto 

 eluded detection but which are the real causal agents of the 

 lesions and symptoms produced. 



17. If such an hypothesis should ultimately prove to be 

 correct, how would it affect our ideas as to the possibility of 

 transmutation occurring amongst bacteria? Obviously, if it is 

 possible for the enzyme or enzymes which produce a certain 

 disease to become dissociated from the organism to which that 

 disease is commonly attributed and to become attached to some 



