1890 



KINETICS OF PHOTOSYNTHESIS 



CHAP. 37D 



(downward run, triangles); a sojourn in the C02-deficient bicarbonate solu- 

 tion causes, however, a rapid adaptation to bicarbonate, illustrated by the 

 dots obtained in a subsequent "upward run." It thus appears that Chlorella 

 and Scenedesmus exposed to high CO2 concentrations lose the capacity to 

 take up bicarbonate, but regain it when placed in a medium deficient in 

 free carbon dioxide. 



It will be noted that the saturation rate in fig. 37D.2 is not affected by 

 the "hysteresis loop," in contrast to Warburg's suggestions (c/. section 4(a)), 



1.0 L2 



p CO, in %a1ni. 



• Fig. 37D.2. Adaptation to bicarbonate (after Gaffron and Rosenberg 1953). Scene- 

 desmus in 2 X 10 ~3 M bicarbonate. After incubation in 50% CO2, cells were transferred 

 into 4% CO2 and illuminated until all CO2 was consumed (lower curve). After 1 hour, 

 4% CO2 was added and cells illuminated until all CO2 was again used up (upper curve). 



Steemann-Nielsen (1947) described in more detail the results of experi- 

 ments on penetration of bicarbonate into the leaves of aquatic plants, sum- 

 marized in an earlier note (1946). The question asked on p. 888 in con- 

 nection with that note — whether the transportation of bicarbonate ions 

 across the leaf, first noted by Arens, can be quantitatively significant for 

 photosynthesis — had already been answered in the 1947 paper (see also 



