

: sia . , “ i ; °F 
rw - , d Ww a 
«tj "3 i 
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s =¢ 
sina moar / aa 
hy “< 

In my own experiments, dealing with the major 
is ssue, I have invariably used hermetically sealed 
flasks or tubes, and the experiments have either 
been carried out in the manner I[ have just de- 
scribed, or else by adopting the equally safe method 
of Needham and Spallanzani. 

