102 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



the growth of B. coli without affecting the development of B. typhosus 

 and B. paratyphosus. 



Electrically-controlled Low Temperature Incubator.* — L. A. 

 Rogers has described the following arrangement for a low temperature 

 incubator. It is adapted from a small refrigerator (fig. 13) by putting in 

 an insulating partition between the ice box and the lower chamber ; a 

 f inch lead pipe C is coiled in the bottom of an ice box, and in the 



MSTg, 



Platiwv. 



P\ 



a 



la 8oa 



rCoiL 



-Heating cons. 



-Rubber block . 



--Wood 6*st. 



- -Rubber block. 



Fig. 13. 



Fig. 14. 



lower chamber D D ; the ice rests on the coil C which is connected with 

 a reservoir A containing a float valve, to insure a constant pressure ; the 

 other end of the pipe is connected with the waste. A slow current of 

 water through the coil will reduce the temperature of the lower chamber 

 below 20° C. ; the temperature may then be raised and maintained at 

 any desired point by an electrical device. This consists of a resistance 

 coil for heating, a bimetallic regulator connected with a low voltage 

 circuit obtained from resistance coils, and a circuit-breaker operating the 

 heating circuit. The regulator is composed of two strips of brass and 

 ivar (a nickel-steel alloy) each £ by \ by 15 inches, riveted together and 



Centralbl. Bakt., 2te Abt., xv. (1905) p. 236. 



