CARBON DIOXIDE EXCHANGE DURING THE SHORT INDUCTION PERIOD 1347 



Culture conditions and micronutrients were found to have an important 

 effect on the size of the gush (as mentioned in chapter 29 in the discussion 

 of the influence of these factors on the apparent quantum yield of photo- 

 synthesis). Anaerobic incubation prevented the gush {cf. section 6). 



The formal analogy between the observations of Emerson and Lewis 

 and of Blinks and Skow is unmistakable. Both observed an initial libera- 

 tion of carbon dioxide in light, compensated by absorption in a subsequent 

 dark period. However, the gushes of Blinks and Skow lasted for only a few 

 seconds, as against several minutes in the experiments of Emerson and 

 Lewis. Perhaps, the "cusps" visible on BUnks and Skow's curves were 

 all that remained of the "Emerson-Lewis effect" at the (undefined, but 

 probably low) carbon dioxide concentration used by these investigators. 

 Blinks and Skow gave no hints as to the volume of the alkaline "gush"; 

 but a glance at their figures makes this appear to be equivalent to the photo- 

 synthetic production in a few seconds of strong illumination, thus five or ten 

 times smaller than the carbon dioxide gushes of Emerson and Lewis 

 (stated above to be roughly equivalent to the amount of chlorophyll, and 

 thus equal to the photosynthetic production in 20 or 30 seconds of strong 

 illumination). 



Warburg and co-workers (1948, 1950, 1951) did not usually observe a 

 significant carbon dioxide gush ("Emerson effect") in Chlorella even while 

 they worked with carbon dioxide concentrations of 10% or more. Nish- 

 imura, Whittingham, and Emerson (1951) suggested that physical lag in 

 the equihbration of the manometer may have approximately compensated 

 for the burst, and created the impression that both were absent. (Con- 

 cerning claims of ehmination of the lag by rapid shaking, cf. p. 1111.) 



A clear and unambiguous confirmation of the occurrence of the CO2 

 burst was provided more recently by Brown and Whittingham (1955) 

 using the mass spectrographic method. 



Warburg and co-workers (1951, 1953) concluded, from two-vessel 

 manometric measurements, that a carbon dioxide gulp, rather than burst, 

 took place in the first minute of illumination in Chlorella, parallel with the 

 oxygen burst; since the Qp ratio they calculated was about 0.85, the CO2 

 gulp must have been even larger than the O2 gush. (However, this ratio 

 was an average for the total gas exchange in 6 minutes of illumination, 

 leaving the distribution of carbon dioxide exchange over this period open; 

 furthermore, the determination of Qp was the least reliable part of these 

 measurements.) 



The induction curves of Emerson and Chalmers (1954), obtained with 

 two- vessel technique of much improved precision, almost invariably showed 

 a carbon dioxide burst, but its volume varied strongly in dependence on 

 temperature, carbon dioxide concentration and cell density. A more rapid, 



