ii6 TECHNICAL ANALYSIS OF 



therefore, above all, work with the two liquids mentioned. It 

 would also be desirable for the hygienist to be able to make 

 direct experiments, but he cannot make use of the human 

 body for this purpose, and in the place of this he has, there- 

 fore, to be satisfied with artificial nutritive substances. What 

 I have just stated is so obvious that it really surprises me that 

 it is necessary to call attention to it. 



It is evident that the results of this zymotechnic method 

 are not comparable with those obtained by means of the 

 hygienic method alluded to above ; this will be readily under- 

 stood from what follows. There are special problems relating 

 to the physiology and technology of fermentation which are 

 different from those relating to hygienic bacteriology, and in 

 each case, therefore, special methods must be elaborated.* 



Starting from this point, of view, I made the following 

 experiments. Small flasks were charged with the nutritive 

 liquids, beer and wort, and closed with cotton-wool plugs. 

 The Chamberland flasks, or better still, the cylindrical Freu- 

 denreich flasks, are very suitable. I employed flasks of 

 this description having a capacity of 22 cc., and into each 

 were introduced about IO cc. of the liquid. A considerable 

 number were simultaneously sterilised in steam under pres- 

 sure. This method is especially suitable for beer which, as is 

 known, it is difficult to sterilise without its undergoing a great 

 change ; as has been emphasised, it is desirable to approxi- 

 mate as closely as possible to the conditions obtaining in 

 practice. Possibly still better results could be obtained by 

 sterilising the beer by filtration (e. g. by means of a Chamber- 

 land filter), and under such conditions that neither the alcohol 

 nor the carbonic acid could escape ; it would, however, be 

 considerably more troublesome to work in this manner. The 

 wort can, of course, also be sterilised by merely boiling it. 



* The word " method" is used here in the same sense in which it is generally 

 employed in modern physiological and chemical literature it does not signify new 

 principles for investigation, but working methods, technical appliances, and 

 modes of manipulation. 



