On tfie Physiology of the Photoautotrophic Purple Bacteria 345 

 F 



performed in a liiminostat designed so that its various compart- 

 ments received different amounts of light energy. This was at- 

 tained by regulating both the power of the lamps and the dis- 

 tance of the lamp from the culture. The light exposure was con- 

 tinuous. A layer of running water (3.5 cm) between the experi- 

 mental vessels and the lamps absorbed the heat radiation of the 

 latter. 



The measurement of light intensity was carried out with a 

 thermal column calibrated for conversion of light energy to 

 erg/cm^ sec; and with the aid of the Goriayev chamber we 

 estimated the cell yield; the inoculum was always carried out 

 with similar amounts of homogenous material. 



Table 3, containing data regarding the dynamics of the cul- 

 ture development in the course of ten days under conditions of 

 varied intensities (from 1.4 X lO^ erg/cm^ sec. to 6.28 X lO^ 

 erg/cm^ sec.) shows that at comparatively low intensities of 

 light ( — 1.4 - 3.4 X 103 erg/cm^ sec. ) the bacteria showed marked 

 development; however, at the very lowest intensities ( — 1.4 X 

 10^ erg/cm^ sec. ) the development on the third day was very slow 

 (only 5.95 million cells per ml) as against 18.3 million cells 

 per ml when the intensity is 6.28 X 10^ erg/cm^ sec. 



TABLE 3 



The Dynamics of Development of Chr. vinosum at Exposure 

 Intensities from 1.4 to 6.28x10^ erg/cm^ sec. 



The difference in the yield between specimens growing 

 under different conditions of light exposure has been observed 

 throughout the entire experiment; however, if the cell yield of 



