No. 3-] BIOLOGY OF THE STENTORS. 



543 



Having reached the extreme left-hand portion of the frontal 

 field the grains drop down into the buccal pouch {b.p), within 

 which they are rushed back and forth several times, until 

 finally they slip into the inner turn of the spiral, thence 

 through the mouth opening at its apex into the endoplasm 

 (see arrows in Fig. 62). I have once or twice seen the grains 

 take a definite path through the endoplasm, so as to suggest an 

 oesophagus, but usually one sees nothing to indicate the 

 presence of one. I have not seen the " Schlundstrang " 

 described by Schuberg (-90), either in the living animal or in 

 sections. Schuberg himself says it is in evidence only at the 

 time fine food-particles are being taken in. 



The grains of carmine speedily become distributed, either as 

 single grains or little clusters, throughout the anterior part of 

 the animal, but penetrate more slowly into the posterior 

 portion. The dissemination is evidently brought about by the 

 circulatory movements of the cytoplasm. On examining a 

 specimen that had recently been fed with carmine, I was unable 

 to detect that the carmine-masses lay within digestive vacuoles, 

 and repeated scrutiny failed to reveal any vacuolar space around 

 the food-masses. I do not think, however, that a digestive 

 vacuole was absent, but believe it was either very small or 

 wholly obscured by the dense cytoplasm. 



The manner of capturing a living prey is different from the 

 almost mechanical inception of non-motile food-particles. I 

 have observed the capture of a small "skipping" Hypotrich of 

 undetermined species. Notwithstanding the rapid and vigorous 

 swimming powers of these little Infusoria, they are frequently 

 entrapped in the powerful vortex of a Stentor, and thereby get 

 drawn into the buccal pouch. Instantly the lips of the pouch 

 (velum and buccal fold) close nearly together, making escape 

 almost impossible. The captive then darts from end to end of 

 the pouch. After a few seconds of this shuttle-like motion, the 

 prey is driven into the inner spiral, thence through the oral 

 opening, always accompanied by a bulk of water several times 

 its size, into the endoplasm. The vacuole thus formed is 

 speedily carried away from the oral aperture, but the In- 

 fusorian within still darts about for a minute or so before 



