402 WM. A. KEPNER AND W. CARL WHITLOCK 
out into the deeper regions of the drop after capturing the two 
flagellates. 
During the course of this observation it was noticed that an 
ameba does not of necessity react to an object that is setting up 
currents in the surrounding water or that is colliding with the 
ameba repeatedly; for before, during, and after the reaction of 
the ameba to the above two Chilomonases, a very active, dense 
swarm of bacteria plied to and fro against the side of the ameba 
making frequent contacts with it. At none of these contacts 
did the ameba react to this highly motile mass. It mattered not 
whether the contact were made at an angle between pseudopodia, 
as at A, figure 6, or at the tips or sides of the pseudopods. 
A newly formed pseudopod that is taking part in the forma- 
tion of a food vacuole may further react to cooperate with a 
part of the body proper to construct a second food vacuole. 
That such is the case is shown by the following example. Two 
Chilomonases were being surrounded by pseudopods a and a' 
(fig. 7). When a had grown to contour 6, a third Chilomonas 
came up by the side of a' . In reacting to this third Chilomonas, 
the body proper threw out pseudopod c', while pseudopod h sent 
out c to meet c' . In this manner all three flagellates were 
captured. 
On March 19, 1918, we saw an advancing pair of pseudopods, 
a and h, encounter a relatively large piece of foreign matter as 
they advanced about a Chilomonas which lay in position indi- 
cated in figure 8. At this synchronous contact of the two 
pseudopods the one, h, was arrested while a advanced to contours 
c and d, d finally fusing with the body proper. The Chilomonas 
was next overarched and captured. 
Perhaps a more striking example of a reaction involving for- 
eign matter is presented in our observation of an ameba ingesting 
a Paramecium that lay in a shallow bay by the side of a large 
brown mass of detritus (fig. 9). The ameba was advancing in a 
general way toward the Paramecium along pseudopods 1, 2, and 
3. As it approached the ciliate, pseudopods 1 and 2 widened 
and partly fused to form a large bi-lobed extremity, m-vi\ 
When this extremity had nearly touched the Paramecium, it sent 
