182 Transactions of the Soeietij. 



Dr. Klein in his vahinLle papers on " Micro-organisms and Disease " 

 has given a definite form and certainty to the utter improba- 

 bihty of Biichner's so-called results being in any scientific sense 

 accurate. 



But the fact that there is no evidence of any direct relation 

 evolutionally between two such forms as B. suhfilis and B. anthracis, 

 the fact that there is no ready way either naturally or artificially of 

 their being changed into each other, must not blind us to the fact, 

 as biologists, that such an evolutional relation in the past is 

 eminently probable, nay almost certain. It may, in all probability 

 must, have taken an indefinite time in the past to effect ; but being 

 once efiected, the specificity is continued as in every other form by 

 inheritance. 



That no means now at work, or capable of being brought into 

 play, is sufiicient to-day to change the B. suhtilis into B. anthracis, 

 it is decidedly both in harmony with fact and philosophy to doubt ; 

 while it is of the utmost importance, if it be within the compass of 

 human research, to discover what these conditions are. 



Cognate with this question is the true interpretation of the real 

 meaning and value of the attenuated intensity of the virus cultures 

 of Pasteur and others. Is the diminished virulence of a given 

 culture, which, as in the case of inoculation for anthrax, pro- 

 duces a mild form of the disease, leading to subsequent immunity, 

 attributable to true biological change in the organisms brought 

 about by changed environment, or is it a mere physical and 

 accompanying chemical attenuation, consequent upon enfeebled 

 nutrition, or extended dilution, of some element of the original 

 virus outside the organism ? 



We can only answer, it is highly probable. What we know of 

 the septic organisms leads us to infer that their tendency to adapt 

 themselves to considerable variation of external conditions is 

 evident ; but this does not of necessity involve permanent change 

 in the organism. 



Now you are well aware that there is at this moment very 

 much more that is similar to, or cognate with, what I have hitherto 

 passed in rapid review, that relates to microscopic biology, and that 

 stimulates, almost provokes, our consideration. 



But in it all there is so much happily that is progressive, and 

 therefore that is of necessity tentative, that I am fain to turn from 

 these multitudinous and deeply interesting matters, feeling that 

 I can better promote the interests of knowledge such as we seek, 

 by the addition of definite facts, than by the most careful and 

 extended review of the progression of knowledge, where much is 

 unfinished, and some things are still in doubt. 



Any President of this Society may be the more satisfied with 

 such a course, who remembers the state of comprehensive efficiency 



