t 783 ] 



stove for heating the water contained in a boiler surrounded 

 with a flue ; (3) a condenser for receiving and condensing 

 the steam passing from the boiler on the stove through 

 a coil of pipe passing in contact with the distilled water coil in 

 the covered up shelf of the chamber into the condenser; (4) 

 two India-rubber tubes connected with the gas pipe, the nar- 

 rower one allowing a small quantity of gas always to pass to 

 keep the flame continuously burning a little, and the larger 

 one, instead of passing directly to the gas burner, passes 

 through a meter or indicator which automatically adjusts the 

 passage of gas through this tube. When the gas burner is 

 fully supplied with gas, the heat produced is great, and the 

 distilled water in the coil is heated and its bulk increased. If 

 the heating is more than enough, a column of water will be 

 seen rising in the glass tube or indicator. This column will 

 exert pressure on the India-rubber disc alongside which the gas 

 has to pass. This pressure is sufficient to close the aperture 

 through which the gas passes either wholly or partially, dimi- 

 nishing automatically the flame under the boiler. The tem- 

 perature in the chamber is thus kept uniformly at 35C. in the 

 lowest shelf, and 32C. in the next, and about 29 in the top 

 shelf. The top shelf may be wholly set apart for those flasks 

 which have been just sown with the seed, and the next shelf 

 for flasks with seed sown the previous day. On the third day 

 the flasks are taken out, all but a fourth or fifth part of them, 

 and removed to a cool place to prevent further vegetation, for if 

 the temperature was above 26 or 2 r jC., quick vegetation will 

 continue, and the filamentous character of the vaccine would 

 be changed into sporular, and vaccination with such vaccine 

 would not be certain. When vegetation proceeds rapidly in 

 the etuve for the first three days the flasks are in it after the 

 sowing of the seed, there are very few spores formed, but 

 afterwards there is more profuse spore formation, unless the 

 vegetation of the vaccine is retarded by being kept in a cool 

 place (23C.). A fourth or fifth portion of the flasks is allowed 



