46 THE BIOLOGY OF STENTOR 



large and much too few in number to correspond to the ecto- 

 plasmic granules. It is possible that the latter, if they do in fact 

 contain an oxidase, may be a new type of oxidative center different 

 from mitochondria, located next to the ciliary rows to assist in 

 their energy metabolism. Such alternating rows of ''mitochondria" 

 and cilia have been described in other cihates by Horning (1927) 

 and Turner (1940). Clearly, the function of these granules calls for 

 further investigation. However these questions may be resolved, 

 Andrews was probably right in saying that the degree of pigmenta- 

 tion is a delicate indicator of the physiological state in stentors 

 (see p. 274). Healthy coeruleus capable of long survival on slides are 

 invariably well colored. 



Nothing is known concerning the origin of the bodies in the 

 granular stripes. In the blue Folliculina ampulla, closely related 

 to stentors, Faure-Fremiet (1932) found many blue granules very 

 close to the macronucleus yet he did not suggest that they were of 

 nuclear origin. Stentor coeruleus also frequently shows pigmented 

 granules surrounding the macronuclear nodes. Perhaps it is 

 relevant to mention that when I grafted a nearly colorless coeruleus 

 to another which was deeply pigmented the fusion mass became 

 well pigmented throughout in the course of 4 hours, far more 

 rapidly than in the usual regeneration of pigment in faded stentors 

 left to themselves. A closer following of such cases as well as of the 

 regeneration of pigment in animals which have been artificially 

 depigmented through chemical treatments, or of similar studies on 

 colorless stentors in which the granules have been artificially 

 sloughed, would seem to offer considerable possibilities for 

 obtaining clues regarding their origin. 



The chemical nature of the pigments themselves is of interest. 

 Of these there seem to be three, as Johnson remarked : the blue- 

 green which gives the name to coeruleus and is probably also found 

 in the similarly colored introversus, multiformis and amethystinus, 

 if not in the related blue Folliculinids ; the brown pigment in niger 

 and possibly also in Johnson's nigricans variety of S. igneus; and a 

 purplish-red in igneus which may be the same as the zoopurpurin 

 of Blepharisma. Only the first two have so far been studied. 



The pigment of coeruleus was given the name "stentorin" by 

 Lankester (1873) in a pioneer work in which he remarked the 

 extraordinary stability of this substance, not dissolved by fat 



