20 KANSAS UNIVERSITY SCIENCE BULLETIN. 



sealed at its other end to a burette, b, graduated into divi- 

 sions of yV of a cubic centimeter. The sugar solution to be 

 tested is introduced by pouring the liquid into the long arm 

 of the apparatus. The end of this arm is then stopped by 

 the thumb, and the apparatus so inclined that the liquid is 

 made to flow into the bulb. The long arm is then plugged 

 with cotton, and the whole sterilized in the autoclave. In 

 inoculating the broth the apparatus is inclined, after removal 

 of the plug of cotton, until a small quantity of the nutrient 

 fluid flows into the connecting neck ; and the yeast or bac- 

 teria are introduced by means of a platinum loop sealed to 

 the end of a long glass rod or tube. By bringing the appar- 

 atus to an upright position again the inoculated portion of 

 broth is made to flow back into the bulb. If this is done 

 carefully no nutrient fluid flows into the graduated arm. A 

 piece of sterilized cotton is then pushed into the graduated 

 arm until it reaches the point, p, where the U-connection is 

 attached. The apparatus is then fixed in a clamp and the 

 opening of the long arm placed in water from which air has 

 been recently driven by boiling. 



By means of a stiff rubber tube inserted far into the gradu- 

 ated arm, air is exhausted from this arm until water rises in 

 it to a point previously determined. When results from two 

 fermentation tubes are to be compared, this point is at such 

 a level that the same amount of air intervenes in each tube 

 between the top of the water column and the surface of the 

 nutrient liquid in the bulb. Thus the error due to the ex- 

 pansion or contraction of different volumes of air, as the tem- 

 perature rises or falls, is avoided. In adjusting the water 

 columns to their zero points, the fermentation tubes are raised 

 or lowered in the vessel of water at their base until the two 

 columns of water are of the same height. The fermentation 

 tubes are then placed in an incubator and kept at a nearly con- 

 stant temperature. 



This apparatus was found very satisfactory for comparison 

 of gas production of two types of micro-organisms, since all 

 gas formed is retained, readings are easily obtained, and the 

 apparatus is so compact that the two tubes may easily be 

 placed together in an incubator. Since the whole apparatus 



