204 



STUDIES ON RESPIRATION. XIlI 



lines at X and Y indicate two glass tubes running off at right angles 

 and connecting (at the points marked Xi and Y] in Fig. 1, B) with 

 another tube, composed partly of glass and partly of rubber. The 

 central portion of this tube (R, Fig. 1, B) consists of a piece of rubber 

 tubing^ 2 mm. in thickness and 7 mm. in diameter (inside) which is 

 joined to glass tubes at W and Z. The ends of the glass tubes are 

 about 1 inch apart. In order to avoid leakage, the rubber tubing is 



Fig. 1. (.1) Apparatus for measuring the production of COo. Organisms are 

 placed in the tube O and the COo is carried over into the tube I which contains an 

 indicator. The tube N contains NaOH for absorbing CO2 when this becomes 

 necessary. 



(B) The rubber tube R is compressed at intervals, forcing air through the valves 

 V and Vi and so maintaining a circulation throughout the apparatus. 



^ Experiments are in progress with a view to replacing the rubber by other 

 materials. 



