FINE STRUCTURE 47 



solvents, acids, or alkalis. But Prowazek (1904) found that 

 sulphuric acid turned it red, potassium hydroxide caused it to 

 become grass-green and osmic salts changed it to black. Weisz 

 (1950a) could bleach stentorin with chlorine gas or potassium 

 permanganate followed by oxalic acid. Stentors of this species 

 appear red by reflected light and blue-green by transmitted (see 

 frontispiece), which is also the appearance of blue Folliculinids 

 (Andrews, 1923). Correspondingly, Lankester demonstrated two 

 strong absorption bands, one in the red and one in the green. 



Prowazek grew coeruleus at higher than normal temperatures 

 and one of the effects he reported was that the animals often 

 became more reddish and showed fluorescence, warming in 

 general producing deeper hues of color. He also found that most 

 animals which feed on coeruleus do not digest the pigment, though 

 the color may be altered somewhat in passage through the alimen- 

 tary canal, as specifically confirmed by Gelei (1925) for the worm 

 Stenostomum. Only certain species of a worm(?), Nuclearian, 

 which grew in some of Prowazek's stentor cultures could assimilate 

 their pigment and become colored throughout. Cannibalizing 

 stentors do not assimilate the pigment of their own species but 

 concentrate and eject it as a dark green excretion vacuole, according 

 to Gelei (1925) and Andrew^s (1955), and this has also been my 

 impression. So also in the resorption of oral parts in the trans- 

 formation of Folliculinids the blue pigment granules are not 

 metaboHzed (Faure-Fremiet, 1932; Andrews, 1949). 



In niger, Maier (1903) noted that the yellow pigment was of the 

 granules and could be dissolved by chloroform to give a red 

 solution. This unique pigment was later studied by Barbier, 

 Faure-Fremiet, and Lederer (1956), who found it to be soluble in 

 alcohol and of two components. A minor component was brown in 

 color and eluted by ether. The major portion, eluted by ether with 

 2% ethanol, was a substance of red-violet color which they called 

 '' stentorol ". The latter could be dried to a dark powder, showing 

 in ultraviolet a red fluorescence which was changed to yellow or 

 blue after various treatments. Absorption spectra were obtained 

 using diflferent solvents, leading to the identification of the pigment 

 as a polycyclic hydroxyquinone. They were impressed by the 

 resemblance to hypericum, a photodynamic substance originally 

 discovered in plants of that name. 



