No. 3-] MORPHOLOGY OF THE STENTORS. 48 1 



Stripes. — In all species of Stentor the body and frontal field 

 are adorned with alternate bright (" Zwischenstreifen " of 

 Biitschli) and granular (" Rippenstreifen," Butschli) stripes. 

 Those of the body have a longitudinal course from the adoral 

 zone to the foot ; while the frontal stripes sweep in a left-handed 

 spiral from the aboral portions of the zone, over the whole 

 frontal field, and down the pharyngeal funnel to the oral apert- 

 ure (Figs. 3 3» 37» 40). As we shall see later, the frontal stripes 

 are the modified derivatives of stripes on the ventral surface. 



The stripes are due to a difference in structure in the ecto- 

 plasm, the protoplasm of the bright stripes being more hyaline 

 than that of the granular bands. The striation is naturally 

 most conspicuous in species that possess pigment, for this is 

 restricted to the granular stripes. Where pigment is absent 

 and the endoplasm is rendered opaque by symbiotic algae, as in 

 5. polymorphus and 5. pyriformis, the stripes are generally not 

 seen at all in the living animal, but may be demonstrated by 

 treatment with aceto-methyl-green, aceto-gentian-violet, or osmic 

 acid. If specimens of the same species, however, happen to 

 be nearly free of chlorophyll, the stripes are visible in the 

 living animal. In 5. roeselii, again, the stripes are obscure, 

 owing to the slight differentiation between hyaline and granular 

 portions. 



The only species I have found suitable for the study of the 

 stripes is 5. ccBruleits. Here their course can be followed with 

 comparative ease. The relative width of granular and bright 

 stripes varies exceedingly in different parts of the body, and 

 the frontal granular stripes are always much narrower than the 

 granular stripes of the body. The relative width of granular 

 and clear stripes at a point just under the adoral zone is seen 

 in Fig. 6, g. s., c. s. Here the granular bands measure 22/*, 

 the clear bands about 'J^^. in width ; but the average for the 

 whole body would be considerably less. It is worthy of note 

 that the gradual diminution in the width of stripes from the 

 anterior to the posterior end of the animal takes place almost 

 wholly in the granular stripes. 



It was long ago pointed out by Stein ('67, p. 227), and has 

 since been noted by Brauer ('85), Gruber ('86), and Schuberg 



