32 



DE. BASTIAN ON THE 



This first criticism is, therefore, quite invalid ; it was directed 

 towards a requirement which I had borne fully in mind from the 

 commencement of these experiments, and had fully met. 



(2) Is the method of the " control " experiment legitimate in such 

 investigations ? or must we in each case allow an interval of some 

 days to elapse hefore hreahing the liquor-potasscB tubes? — Dr. 

 Eoberts says *: — " It is not sufficient to rely in such a case on a 

 control-flask or retort. Each flask or retort should have its own 

 individual sterility tested, because it is practically impossible 

 to apply the heat exactly in the same degree in any two cases." 

 To this I demur, and maintain that where the results are checked 

 and verified by a large number of trials, the method of tbe control 

 experiment is a more accurate and scientific method than that to 

 which he and, following him. Professor Tyndall had resort. This 

 position is based upon the following considerations. 



First, it may be premised that the method of the " control " ex- 

 periment has hitherto been babitually practised by many eminent 

 investigators, and that it has always been thoroughly relied upon 

 in cumulating evidence which was believed to be in favour of the 

 "germ theory." 



Secondly, Dr. Eoberts's objection to its use in these experi- 

 ments carries all the less weight with it because, as I have many 

 times ascertained both before and since the publication of my 

 first results, an exposure of two or three minutes' duration to the 

 temperature of 212° Fahr. always suffices to sterilize a urine of 

 average acidity, whatever tbe incubating temperature to which it 

 may subsequently be exposed. Moreover, previous to the an- 

 nouncement of my results the undeviating verdict of other 

 experimenters with urine — the verdict of Pasteur, of Sanderson, 

 of Lister, of Tyndall, and even of Eoberts himself — had been that 

 after boiling it for two or three minutes, urine kept in a warm 

 place, and free from extraneous contamination, always remained 

 pure t. Such an amount of heat had invariably been found suffi- 

 cient to sterilize it. Why, therefore, when dealing with such a 

 fluid, could it be necessary to wait in each case before the liquor- 

 potassae tubes were broken ? 



In further support of the efficacy and trustworthy nature of 

 the method adopted by me, I may state that I have several times 

 repeated it in this manner : — Selecting any one at random from a 



* 'Proceed, of Eoyal Society,' No. 170, vol. xxt. p. 455, note. 



t See quotations to this effect at p. 2. 



