208 



THE AMERICAN MONTHLY. 



[November, 



freshly cultivated in clear bouillon de 

 poule, exhibit a murderous fatality 

 when inoculated under the skin of 

 previously healthy fow^l. while the 

 same micro-organisms, in equal num- 

 ber and activity, taken from a culti- 

 vation mixture which has been freely 

 exposed to the air for a long time, 

 are devoid of this property? To 

 suppose that a morphological change 

 can account for the observed differ- 

 ence in effects is, if not actually ab- 

 surd, at least entirely unwarranted ; 

 and the only explanation is that the 

 micro - organisms in question have 

 nothing to do directly with the poi- 

 soning effects we are considering, but 

 that they are due to a specific chem- 

 ical product which is present in the 

 freshly cultivated mixture, but which 

 is absent in the stale mixture. Pos- 

 sibly it is destroyed by oxidation car- 

 ried on by atmospheric oxygen. 



Again, in the thirteenth annual re- 

 port of the Local Government 

 Board, Dr. Klein has described ex- 

 periments which seem at first blush 

 to indicate a variability in the degree 

 of virulence of the Bacilhis an- 

 thrasis^ but further experiments 

 proved that the observed facts were 

 ' irreconcilable with the assumptions 

 (i) that the bacillus is in reality 

 capable of undergoing a diminution 

 of its physiological activity — that is, 

 suffering a real attenuation, and (2) 

 that there exist anthrax bacilli having 

 an intrinsic virulence pf various de- 

 grees.' He then adds, ' The fact 

 seems, however, capable of another 

 explanation. Owing to different 

 conditions of growth, for example, 

 high temperature, or other artificial 

 conditions, or owing to different soil 

 on which they grow, for example, 

 the body of a mouse or of a guinea- 

 pig, the bacilli, although themselves 

 the same, embody or appropriate, 

 chemically or otherwise, some new 

 or different substance, which produces 

 the alteration for a particular species 

 of animals. Whether this substance 

 is comparable to a ferment or not, I 

 am not in a position to say ; possibly 



it is some ferment produced by the 

 new conditions.' 



It will at once be seen that Dr. 

 Klein almost embraces the chemical 

 theor}^ of disease, which for some 

 years I have persistently advo- 

 cated ; at least, he has himself fur- 

 nished evidence which gives immense 

 support to m}' views. 



Prof. Virchow also, while hesita- 

 ting to allege the inadmissibility of a 

 mechanical hypothesis of disease 

 caused by micro-organisms, yet clearly 

 thinks the assumption of chem- 

 ical action remains as the only 

 real explanation, as will be evident 

 to all who are conversant with his 

 writings, and notably with his article 

 on ' Infectious Diseases in the Army,' 

 which has been translated from the 

 German by Dr. J. James. 



The chemical theoiy places us at 

 once upon ground with which we 

 are familiar, and gives us an assur- 

 ance of security. Just as the yeast- 

 cell decomposes a solution of sugar 

 by the agency of a soluble zymase 

 which it is supposed to produce, and 

 as the Mycodertna aceti oxidizes 

 (by the assistance of the air) alcohol 

 into acetic acid, and as the Bacte- 

 rium lactis sours milk and produces 

 lactic acid, so also do the micro- 

 organisms which initiate putrefaction 

 produce definite chemical products, 

 which act as blood -poisons ; and the 

 micro-organisms which are known 

 to be intimately associated with certain 

 specific diseases act as the excitants, 

 not in a primary or mere mechanical 

 sense, but in a secondary sense, viz., 

 b}^ the agency of chemical substances 

 elaborated bv them under suitable 

 conditions. 



These reflections necessarily take 

 us a step further. If there be no 

 sugar present in its soil, the' yeast- 

 plant can not produce alcohol ; but 

 it is not to be assumed (at least, in 

 the absence of sufficient evidence) 

 that this micro-organism can live 

 only upon sugar. It is highly prob- 

 able, indeed, that any one micro- 

 organism can live and thrive under a 



