THE RATE OF CO(2) ASSIMILATION BY PURPLE BACTERIA AT VARIOUS WAVE LENGTHS OF LIGHT.

1. The relative absorption spectrum of the pigments in their natural state in the photosynthetic bacterium Spirillum rubrum is given from 400 to 900 mmicro. The position of the absorption maxima in the live bacteria due to each of the pigments is: green pigment, 420, 590, 880; red pigment, 490, 510, 550. 2. The relative absorption spectrum of the green pigment in methyl alcohol has been determined from 400 to 900 mmicro. Bands at 410, 605, and 770 mmicro were found. 3. The wave length sensitivity curve of the photosynthetic mechanism has been determined and shows maxima at 590 and about 900 mmicro. 4. It is concluded that the green bacteriochlorophyll alone and not the red pigment can act as a light absorber for photochemical CO(2) reduction.