28 WM. A. KEPNER AND B. D. REYNOLDS. 



becoming disseminated, as though the fragment were a lateral 

 branch which the pseudopod was withdrawing. There is no sign 

 of incoherency or enlargement at this place (see Fig. 5 — A, d). 



(b) The reaction toward foreign fragments is different, as will 

 be brought out later. 



(c) On many occasions it was observed that after fragments 

 had been separated from their cell-bodies for a long time they 

 would cease to move, become rounded off, and take on an opaque 

 granular appearance. The time required to bring about this 

 change depends on several conditions, particularly on the size of 

 the fragment ; a large fragment retaining its power of movement 

 longer, other things being equal. Though it has not been deter- 

 mined experimentally, it is reasonable to presume that the physio- 

 logical condition of such a fragment is changed as well as its 

 appearance ; yet its molecular composition can hardly be so altered 

 as to change its food value. Though over twenty-five observations 

 have been made on the reaction between Difflugia and its fragment, 

 which had assumed a granular, opaque, spherical condition, not a 

 single instance was found in which the animal picked up such a 

 fragment. The following example is illustrative of the reactions 

 obtained : 



On June 10, 1920, at 11 \\J A.M., a large pseudopod was cut 

 from a Difflugia spiralis and the cell-body was then moved out of 

 the field. The fragment moved about for fifteen minutes, then 

 gradually ceased and assumed a spherical shape. By 12:15 half 

 of the bulk constituting this mass of protoplasm showed disinte- 

 gration to such an extent that it had changed from the spherical 

 condition and was scattered, in an uneven manner, around the 

 portion which still retained its rotundity. At this time the cell- 

 body was brought up and the mouth of its shell placed in contact 

 with the fragment. The animal soon extended two pseudopods 

 which came in contact with the fragment in the manner indicated 

 in Fig. 3 — A. For two minutes the animal remained practically 

 passive, then it began to move forward, taking with it the portion 

 of the fragment which was still in a spherical condition. This 

 was held by a secondary pseudopod which had formed an imper- 

 fect cup around it (Fig. 3 — B), the disintegrated portion being 

 left behind. Movement was continued in the same direction until 



