340 WILLIAM M. GOLDSMITH 



to be expanded sufficiently wide for the spiral to pass out without 

 being first unwound. In many instances the mouth was stretched 

 almost the length of the body. However, the author would con- 

 clude from his observations that the stretching of the mouth of 

 frontonia is brought about by mechanical means through the 

 twisting movements considered above rather than through being 

 under the control of the organism itself. At first this unusual 

 process was thought to be simply the breaking of the body wall, 

 but by segregating individuals which had thus ejected rolls 

 of oscillatoria filaments it was found that they were in no wise 

 injured and that the stretching of the mouth was a normal 

 process. Some of the unpublished notes of Schaeffer bear 

 directly upon this point. He says in part: ''In case the thread 

 is too long, the coil does not always unwind but in nearly all 

 cases, if the coil consists of many turns, the coil in its entirety 

 comes out of the animal, the mouth apparently stretching for 

 nearly the whole length of the animal. This is a normal proc- 

 ess and does not hurt the frontonia." The mouth of the fron- 

 tonia is not only expanded to an unusual width during ejection, 

 but also many instances of ingestion, or attempted ingestion, 

 have been noted in which the mouth was pushed open almost 

 far enough to ingest objects as large as the animal itself. Figure 

 13 shows a frontonia attempting the ingestion of a mass of debris 

 larger than its own body. Observations indicate that this 

 enlarging of the mouth during ingestion is brought about by 

 the play of the first two factors involved in ingestion, namely, 

 by the pull of the oral cilia and by the forcing of the organism 

 against and around the material being ingested by the action of 

 the locomotor cilia of the body wall. 



INGESTION OF LARGE DESMIDS 



At times desmids which seemed to be ciliated (fig. 16) were 

 seen to swim here and there through the frontonia cultures. 

 Since the high power revealed a thin layer of protoplasm between 

 the ciliated wall and the body of the desmid (Closterium), it was 

 evident that these unusual organisms were frontonias which 

 had engulfed desmids of more than twice their normal length. 



