1918] Yocum: The Neuromoior Apparatus of Euplotes Patella 347 



a way that the organisms used for food are carried into the funnel- 

 shaped pharynx and then forced into the endoplasm by the pharyngeal 

 cilia. Often while watching Euplotes feeding, small ciliates have 

 been observed struggling violently at the anterior end of the pharynx 

 evidently striving to swim away from the cilia which were forcing 

 them into the gullet. If the victims were large enough they often 

 escaped, but small ciliates and flagellates were usually swept into the 

 gullet and on into the endoplasm. 



In the paragraph above, reference was made to a cavity which is 

 abruptly joined to the cytostome. This will be named the cytostomal 

 recess {cyt.r., fig. A). It extends from the pharynx diagonally for- 

 ward almost to the right anterior edge of the animal. Its shape is 

 difficult to describe but an idea of its form may be gotten from figure A. 

 Posteriorly this cavity lies open for nearly its whole width but 

 anteriorly it extends under the right ventral field for as much as 

 fifteen microns or about half of its width. At its anterior end it is 

 bent to the right and extends under the dorsal wall of the cytostomal 

 field. Being so directly connected with the cytostome it seemed at first 

 that such a recess or diverticulum must be an organ concerned in 

 feeding. However, after a careful study of this in both living animals 

 and prepared specimens, I am unable to see any evidence which would 

 support such a conclusion. Throughout its whole extent it is lacking 

 in cilia, and in no case has it been seen to contain food or any other 

 substance. As to its true function there seems to be little evidence 

 favoring a definite conclusion. However, the following is offered as a 

 suggestion of its possible use. If we look at the ventral surface of the 

 animal, it is seen that a greater part of the cytoplasm lies to the left 

 of the median longitudinal axis. This hollowing out of the body on 

 the left would leave the right half of the body relatively heavier than 

 the left. If now we study the diverticulum of the cytostome in its 

 relation to the median longitudinal axis, we see that the greater part 

 of the cavity lies to the right of the line. Such a location tends to 

 put the center of the mass, in so far as it concerns the right and left 

 halves nearer the median plane, thus bringing the animal more nearly 

 to a bilateral balance of substance. 



It is difficult to see how such a prominent structure as the diverti- 

 culum described above has escaped the observation of such investigators 

 as Ehrenberg, Stein and Kent, for it can be seen in both living and 

 prepared specimens. The fact that it never contains food and under- 

 lies a dense area of the body may account for the oversight. 



