FOOD-REACTIONS OF AMEBA PROTEUS 403 
out a small secondary pseudopod, a, beneath the prey, and h 
anterior to it (fig. 10). When the pseudopods a and h came in 
contact with the detritus, they moved apart and became much 
stouter (fig, 11) . In the meantime a third pseudopod, c, appeared 
projecting from between a and h over the dorsal side of the Para- 
mecium, while a pocket was formed within the body proper of 
the ameba at the bases' of these three pseudopods. The Para- 
mecium first jumped to position 2, figure 11. The excited Para- 
mecium next backed into the pocket of the body proper, 3, and 
a, h, and c closed in and surrounded it completely. 
Usually ameba reacts to a free-swunming Euglena viridis by 
sending out pseudopods that widely embrace it. Sometimes, 
however, the embracing pseudopods close in upon the Euglena 
to hold it in a tight grip behind the position of the gullet, and 
this though the flagellum be quite active. On March 17, 1919, 
we saw a Euglena caught in this manner at its anterior end. 
The projecting part of the flagellate's body was passive, but the 
flagellum was very actively lashing within the enclosed bay. 
All movement for the time being had ceased in the gripping 
pseudopods. This observation had lasted for but a minute more, 
or less when a large Paramecium, coming up at right angles 
to the Euglena, colhded with it at the point indicated by the 
arrow in figure 12, and dragged the Euglena free from the ameba's 
grip. This was apparently the first step in the process of chang- 
ing the second type of reaction into the first type. Mr. C. O. 
Dean, a student in this laboratory, observed an ameba that had 
thus gripped a Euglena viridis and thereby cut off its chance of 
escape. After the ameba had thus laid hold of the Euglena, its 
"ectoplasm flowed out around the Euglena" on all sides and so 
close to the wall of the Euglena that there was no water present 
between "the surfaces of the two organisms." This is not com- 
parable to the food-taking by means of invagination as Prenard 
('05) and Grosse-Allermann ('10) have described for Ameba 
terricola. 
In 1900 the senior author observed a relatively small ameba 
ingest a relatively large Paramecium caudatum. In this case 
the ciliate was surrounded by pseudopods that were sent out 
