PERFORMANCE OF THE EXPERIMENT I// 



specially reserved for these experiments, nor is it 

 possible to allow the incubator to be used at the same 

 time for bacteriological purposes. 



(5) Before starting it must be ascertained that all 

 utensils are to hand and in perfect condition. 



(6) Experiments can only be carried on with good 

 light. It is impossible to carry on more than five or 

 six experiments at the same time with the necessary 

 care. 



(7) Before successful tests can be expected, one 

 must not only be certain of a perfect knowledge of all 

 the details of the method, but a thorough knowledge 

 of their fundamental principles is most essential. 

 It is not sufficient to know the method thoroughly, 

 one must have a perfect command of it, and, as it were, 

 live in it. No one is able to stain tissues perfectly 

 for the first time, even though he be guided by the 

 strictest directions. Even simple chemical methods 

 require practice, and the most elementary analyses 

 sometimes fail. Even the Kjeldahl method, which 

 is so easily handled, requires to be thoroughly learnt. 

 Should a failure result, no one would think of 

 communicating it while blaming the method; he 

 would never rest until the cause of the error was 

 found. The statement, "We have been working 

 in the strictest manner according to the given 

 directions,' I treat with scepticism on the basis 

 of a rich experience. Such great offences are often 



12 



