48 THE BIOLOGY OF STENTOR 



The nature of the pigment in the cortical granules of coeruleus 

 has been reinvestigated and much enlarged upon by K. M. Moller 

 (i960). Instead of Lankester's (1873) spectrometric absorption 

 maxima of 662 m/x and 562 m/x he found with living or extracted 

 stentors, only, a strong band at 618, a weaker one at 568, and a 

 third and very weak band at 527 m/x. This difference can be 

 explained on the basis that Lankester used stentors concentrated 

 in the gut of an aquatic worm, which may have ingested photo- 

 synthetic organisms as well or even S. polymorphus with its algal 

 symbionts. Stentorin itself does not resemble chlorophyll; and 

 tests by Moller and C. Chapman-Andresen demonstrated that it 

 has no photosynthetic action : coeruleus grown in the light do not 

 incorporate C^" bicarbonate solution. 



The predominant blue-green pigment is indeed resistant to 

 solubilization but is dissolved in acetone-water and completely 

 extracted by ethylenediamine. Solutions, hke the living stentors, 

 are dichromatic and appear green by transmitted and red by 

 reflected light, but this is no proof of fluorescence. However, 

 Moller discovered that some races of coeruleus have an additional, 

 ethanol-extractable pigment in the cortical granules which renders 

 them red fluorescent in ultraviolet light of wave lengths from 366 

 to 590 m/x. Because the fluorescence appears only after these 

 stentors are dead or dying — as when dried on filter paper or 

 killed with boiling water — he inferred that the pigment is 

 probably bound to some protein (or carbohydrate) carrier which 

 uniquely quenches the fluorescence in living animals. The produc- 

 tion of this fluorescence is a nuclear-dependent character (see 

 p. 322). Moller and A. H. Whiteley (unpublished) found the 

 alcohol-extracted pigment or aqueous homogenates only of 

 fluorescent stentors to be photolethal (killing action of pigment 

 plus strong light) to Paramecium caudatum, Colpidium, and to the 

 stentors themselves but not to non-fluorescent coeruleus. Yet 

 living fluorescent stentors seemed to affect non-fluorescent 

 animals, but not the reverse, in the same medium (separated by 

 a screen) causing the latter to become colorless, smaller in size, 

 and even fluorescent. 



Both the fluorescent and the major pigment not extractable by 

 ethanol are in their spectrometric and chemical properties different 

 from yet quite similar to hypericin, a photolethal substance 



