OXYGEN EXCHANGE DURING THE SHORT INDUCTION PERIOD 1329 



vessels, whose shape was carefully chosen to achieve the best possible 

 synchronization of the gas exchange processes. 



The importance of the shape of the manometric vessels for the reliability 

 of two- vessel determination was mentioned before on p. 1111. Slight 

 differences in the effectiveness of stirring in the two vessels can become 

 crucial in the analysis of transient phenomena. Emerson and Chalmers 

 (1954) showed this by comparing the manometric data obtained in vessel 

 pairs of different shape with Chhrella cells suspended in carbonate buffers 

 (where only one gas is exchanged). With a vessel pair of the type used by 

 Warburg and co-workers {H and /ii in fig. 29.4A), the course of pressure 

 equiUbration was markedly different in the two vessels, as illustrated by the 

 left side of figure 33. 6C; the synchronization was much better with vessels 

 of the ''Emerson type" {H and ho in fig. 29.4A), as shown by the steadiness 

 of the ratio of the pressure changes during the transition from dark to 

 light and back, on the right-hand side of the diagram. The reason for this 

 difference must be that shaking at a certain rate has a different effect for 

 different distances between liciuid and ceiling. 



Furthermore, vessels "matched" for one gas, are not eo ipso matched 



for others. 



Emerson believes that, because of these experimental uncertainties, 

 Warburg's quantitative analysis of manometric readings in the transient 

 periods (and of the quantum yields derived from this analysis) are open to 

 grave doubts; particularly uncertain is the determination of the carbon 

 dioxide-oxygen ratio (which is the basis for the conclusion that the ob- 

 served bursts involved photosynthesis and respiration as a whole). 



Emerson and Chalmers' measurements (1954) with vessels of better 

 synchronous behavior confirmed that an "oxygen burst" does occur some- 

 times in the first minute of illumination (as first noted by Blinks and Skow, 

 and also indicated by the manometric measurements of Burk, Warburg 

 et al., and by the electrochemical measurements of Damaschke et ah). 

 However, this burst is not a regular feature of photosynthesis in Chhrella; 

 nor does it usually have the volume required by Burk and Warburg's 

 theory. Quantum requirements of 3 (quanta per oxygen molecule), or 

 even less, sometimes can be calculated by comparing oxygen production at 

 the height of the burst {i. e., in the first minute of illumination) with the 

 peak oxygen consumption subsequent to the fight period; however, the 

 latter peak is reached, according to Emerson and co-workers, not immedi- 

 ately after the cessation of illumination, but several minutes later (fig. 

 33. 6D). 



The manometric method is too slow to catch gas bursts or gulps if they 

 are not big enough to affect significantly the gas exchange in a whole 

 minute. Therefore, Emerson's measurements can be used only as a check 

 of Warburg, Geleick and Briese's conclusions concerning the volume and 



