INGESTION IN THE CILIATE, FRONTONIA 343 



only varies with the shape, size, color, density, and flexibility 

 of the ing;ested material, but also with the arrangement as well. 

 Although material of almost any color might appear in the 

 body of the frontonia, the more common colors, especially during 

 the progress of digestion, are the various shades of brown, green, 

 and blue. 



DIGESTION 



Although the problem of digestion need not necessarily be 

 considered with the mechanics of ingestion, a number of simple 

 observations were made along this line. As was suggested in 

 the earlier part of this paper, the smaller solid particles of the 

 cell are not usually found in contact with the long food fibers. 

 This clear space forms the beginning of the future food vacuole. 

 The digestive fluid attacks certain parts of the fibers, especially 

 the ends, more readily than others, and this causes the replacing 

 of the graceful curves by sharp bends, breaks, and general dis- 

 tortion. The walls of the oscillatoria filament give way and 

 after two or three hours of digestion the free ends usually begin 

 to roll up. Later the fibers break at various points and the 

 pieces roll up until only small spherical food vacuoles containing 

 irregular masses remain. The entire process consumes approxi- 

 mately six hours. 



SUMMARY 



1. Observations and experiments were made upon frontonias 

 while these organisms were ingesting euglenas, diatoms, desmids, 

 and oscillatoria filaments. 



2. The ingestion of blue-green algae, especially oscillatoria 

 filaments, furnished the most conclusive demonstrations of the 

 method involved, as the process continued a greater length of 

 time and involved more factors than did the ingestion of smaller 

 organisms. 



3. Five factors are involved in the process of ingestion of 

 material longer than the expanded width of the body of the 

 frontonia. In case of smaller particles, the third, fourth, and 

 fifth factors mentioned below are not essential to ingestion. 



