PURE CULTURES OP 



fitted with a rubber tube which is closed by a glass stopper; 

 the end of the bent tube is plugged with asbestos. 



The metal vessel (Figs. 5 and 6) is made of tinned copper. 

 At first I used Pasteur's model (Fig. 4), but when I discovered 

 its imperfections, and the great difficulty of working with it 

 with safety, I abandoned it. This vessel is closed at the top 

 with a rubber stopper, through which pass a short straight 

 tube for introducing the yeast, and a long bent tube for the 

 exit of the carbonic acid gas ; the top of the vessel is also 

 provided with two windows. Nearly at the bottom is a tap 

 for drawing off the beer and yeast. It is especially at the 



windows and tap that in- 

 fection from without occurs 

 after the vessel has been 

 used a few times. In 

 some laboratories, however, 

 it is still employed, and 

 I have therefore intro- 

 duced the accompanying 

 sketch. In the course of 

 years my assistants and I 

 have contrived the vessels 

 I shown in Figs. 5 and 6 ; 

 the form shown in Fig. 6 

 is used in the Carlsberg 

 laboratory, and I now 

 especially recommend it, but Fig. 5 has the advantage of 

 being cheaper. The name Carlsberg vessel is generally 

 applied to them ; the difference between them and Pasteur's 

 vessel is distinctly shown in the figures. 



Over the short tubes a and b (Fig. 5) are fitted rubber 

 tubes, and these are closed with glass stoppers in the usual 

 manner ; the lower tube b is also provided with a pinch-cock. 

 The metal part of it must be as short as possible, and the 

 pinch-cock closing the rubber should be as close as possible 



FIG. 4. 



