1338 



INDUCTION PHENOMENA 



CHAP. 33 



to absorption of carbon dioxide. As far as the latter is concerned, two or 

 three distinct types can be noted. One (type I) is obtained with wheat 

 plants in an atmosphere of low carbon dioxide content {e. g., normal air; 

 cf. fig. 33. 21 A), and with Chlorella cells grown in an atmosphere rich in car- 

 bon dioxide {cf. fig. 33.22A). It is characterized by a smooth increase in 



I 2 3 4 5 

 TIME, min. 



2 3 4 

 TIME, min. 



2 3 4 

 TIME, min 



After 16 min. In dark After 4 min m dork After 1 min. in dark 



Fig. 33.10a. CO2 absorption by Stichococciis bacillaris at 19° C, as a function of time 



(after Aufdemgarten 1939). 0.32% CO2, varying light intensity. 



carbon dioxide consumption during the whole induction period (3-4 

 minutes). On closer examination, one notices a slight inflection near the 

 origin of the curves (at about 20-30 seconds). Because of the delayed 

 response of the carbon dioxide-recording device, this position of the inflec- 

 tion probably means that the CO2 consumption begins with a "gulp" im- 

 mediately upon illumination (as indicated by the dotted curves in fig. 33.21). 



