98 AMEBOID MOVEMENT 



in feeding. Frontonia feeds mostly, if not entirely, on large par- 

 ticles. It has no oral groove like paramecium has, and when 

 swimming no ciliary vortex is produced such as is seen in para- 

 mecium. Frontonia feeds mostly by "browsing," that is by eat- 

 ing particles lying on or against some solid support, though it is 

 able also to feed upon particles suspended in the water. 



Oscillatoria and Lyngbia and other filamentous algae are the 

 chief food of Frontonia. Filaments of these algae are ingested 

 by pulling them into the mouth and then rolling them up into a 

 coil in the body. Pieces of Oscillatoria six to eight times as long 

 as the Frontonia are readily eaten in this way. 



As a rule the end of a filament is seized by the mouth and 

 gradually passed back into the body (Figure 32, a). As soon 

 as the tip of the filament is well in the mouth and in contact with 

 the endoplasm, streaming begins in the endoplasm in the region 

 of the mouth and takes a direction directly back against the 

 aboral wall, almost, if not quite perpendicular to the longitudinal 

 axis. This stream of endoplasm carries the filament back to the 

 aboral wall, sometimes pushing out the wall a considerable distance. 

 Presently, however, the filament is carried posteriorly along the 

 aboral wall by the streaming protoplasm, which has by this time 

 become rotational, and after reaching the posterior end the fila- 

 ment is brought up along the oral wall. The rotational streaming 

 continues until the entire filament is wound up, which in excep- 

 tional cases may make four or five coils inside the animal. 



The mouth has considerable grasping power. This is shown in 

 Figure 32 where a filament of Oscillatoria was bent upon itself 

 by the mouth and then rolled up in the body by the endoplasm 

 in the same manner as a single filament. The mere viscosity of 

 the endoplasm would be insufficient to bring about the bending 

 of the filament. For the sake of comparison it should be added 

 that a similar grasping power is also present in paramecium. The 

 moment the food vacuole at the mouth is large enough, the endo- 

 plasm pulls it away and moves it rapidly toward the posterior 

 end of the paramecium, much more rapidly than it would be 

 carried by the rotationally streaming endoplasm. But from the 

 posterior end forward the food vacuole is carried at the same 

 rate as are the other particles in the endoplasm. In both Fron- 



