MEASUREMENTS OF GAS EXCHANGE 



139 



(b) 



(c) 



(d) 



(e) 



(f) 



Fig. 10-3. Some examples of special manometer vessels. The rectangular 

 vessel (a) is often used in photosynthesis studies because a greater surface 

 can be exposed to light from below. The sidearms, as in b, permit the 

 addition of materials while the measurement is in progress. Alkali for 

 trapping COo might be placed in the center well, as in b or d, in a con- 

 centric trough, as in c, or added after the experiment is in progress (e). 

 Number f has a reduced volume to permit greater sensitivity of measure- 

 ment. 



The techniques of manometry are not especially difficult to learn. 

 The glassware is fragile but easy to handle, and a variety of kinds of 

 vessels have been developed, including some specialized for certain un- 

 usual measurements. Figure 10-3 shows some sample types. Only a little 

 practice is required to read the manometer scales, even while the 

 manometers are moving. In a short time it is possible to learn to recog- 

 nize the behavior of the manometers when something is wrong. Occa- 



