324 BACTERIA 



of medical and sanitary journals reveal not a few keen con- 

 troversies upon the injurious action of certain substances 

 upon certain bacteria owing to the discrepancies, of neces- 

 sity arising, between results of different skilled observers 

 who have been carrying out different experiments with dif- 

 ferent solutions of the same substance upon different proto- 

 plasms of the same species of bacteria. We feel no doubt 

 that in these pioneering researches much labour has been to 

 some extent misspent, owing to the neglect of a common 

 denominator. Only a more accurate knowledge of bacteria 

 or a recognised standard for disinfecting experiments can 

 ever supply such common denominator. 



Species of bacteria for comparative observation-experi- 

 ments upon the action of chemical or physical agents must 

 be not only the same species, but cultured under the same 

 conditions, and treated by the agent in the same manner, 

 otherwise the results cannot be compared upon a common 

 platform, or with any hope of arriving at exactly the same 

 conclusions. 



Sir George Buchanan laid down, in 1884, a very simple and 

 suitable standard of what true disinfection meant, viz., the 

 destruction of the most stable known infective matter. Such 

 a test is high and difficult to attain unto ; nevertheless, it 

 is the only satisfactory one. Obviously many substances 

 which are useful antiseptics in practical life would fall far 

 short of such a standard, yet for true and complete disin- 

 fection such an ideal is the only adequate one. 



Quite recently three or four workers at Leipzig 1 have 

 drawn up simple directions, the adoption of which would 

 considerably assist in securing a common standard for dis- 

 infectant research. They are as follows : 



I. In all comparative observations it is imperative that 

 molecularly equivalent quantities of the reagents should be 

 employed. 



1 Zeitschr. f. Hyg. und Inf. Krank. , xxv. 



