AIR AND WATER FOR MICRO-ORGANISMS. 117 



In the case of the ordinary cold water used at the Old 

 Carlsberg brewery in September, 1887, 5 cc. were mixed 

 with 5 cc. of the nutritive liquid (in one series beer, in the 

 other wort). One drop (0*04 cc.) of each of these mixtures 

 was added to each of a series of 1 5 flasks containing beer in 

 one case, and another series of 15 flasks containing wort. 

 The drops can be added from a pipette, the upper end of 

 which is connected with a piece of rubber tubing, which is 

 plugged with cotton-wool so as to completely free the air which 

 passes through from germs. The whole is sterilised, fixed on 

 a stand, and the flow is regulated by means of a pinch-cock. 

 In all operations of this kind it is advisable to employ a pure 

 air chamber. It is evident that all apparatus and nutritive 

 media must be sterilised, and that care must be taken to work 

 always with average samples. The quantity of water that is 

 to be used for sowing must be accurately measured so that 

 the result obtained can be calculated on I cc. 



Simultaneously with the above, 0*5 cc. of the same 

 water was examined by means of a plate culture according to 

 Koch's method, and also 0*5 cc. by means of a similar 

 plate culture, but employing wort : gelatine (wort with the 

 addition of about 5 per cent. Of gelatine) in the place of meat 

 extract peptone gelatine. In addition to this, a considerable 

 number of drops of the above mixtures of the water and wort, 

 and of the water and beer, were sown on solidified gelatine 

 plates containing no nutritive liquid. All the gelatine cul- 

 tures were kept moist and covered over with bell-jars, and, 

 like the cultivations in the flasks, were placed in an incubator 

 at 24-25 C. 



The object of this experiment was, in the first place, to 

 obtain accurate information concerning the behaviour of the 

 beer and wort cultures, in comparison with the gelatine cul- 

 tures, and from the results obtained to ascertain which method 

 was most suitable for analyses in the brewery. The object of 

 the last-mentioned gelatine cultures was to determine whether 



