338 WILLIAM M. GOLDSMITH 



shown in figure 5, the usual method of ingestion (the pull of the 

 cilia of the mouth and the push of the locomotor cilia) carries 

 the end of the fiber along the aboral wall to the posterior end of 

 the frontonia (fig. 7, e). The continued pressure exerted from 

 within not only makes more pointed the posterior end, but 

 also causes an elongation of the entire organism (fig. 8). The 

 anterior end now moves along the fiber, thus causing the mouth 

 to be drawn well toward the anterior end of the organism (fig." 

 8,/). As the mouth is pulled forward the pressure at the poste- 

 rior end becomes greater and greater. This is the second tension 

 point in the process. The stimulus causes the organism to 

 again undergo sharp body contractions. As in the former case, 

 if the pressure is not relieved the oral cilia are relaxed, causing 

 the body again to shorten. With a whirling backward move- 

 ment the frontonia ejects the food particle (fig. 12). However, 

 if the fiber bends or breaks, normal ingestion continues. 



In the specific case under consideration, the oscillatoria fila- 

 ment was bent as indicated (fig. 9) and the mouth continued 

 to move along the fiber (fig. 10, h, i, and j), causing the posterior 

 end to be drawn toward the mouth. The whole animal was bent 

 upon itself like a hinge (fig. 11). Since under the given pull 

 the ciliate had now reached its limit of expansibility and, fur- 

 thermore, since the fiber did not bend again, further ingestion 

 was impossible. Accordingly, the frontonia suddenly contracted, 

 whirled about the oscillatoria filament, causing the mouth (m) 

 to be pried wide open, and flung itself from the food (fig. 12). 

 With reference to this particular method of ejection, Schaeffer 

 says: ''If there are several coils of a filament whose other end is 

 fast, rolled up inside of a frontonia, the mouth sometimes stretches 

 antero-posteriorly until the coil as a whole without unwinding 

 is thrown out of the body." 



Rigid fibers were used extensively as food for experimental 

 purposes, as the organism would continue to draw in one of them 

 as long as possible and then eject it, only to repeat the process 

 time after time. Since the fiber was longer than the expanded 

 length of the organism and not sufficiently flexible to be wound 

 up inside of the ciliate, the repeated attempts at complete in- 



