AUTHOR S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, FEBRUARY 7 
FOOD REACTIONS OF AMEBA PROTEUS 
WM. A. KEPNER AND W. CARL WHITLOCK 
University of Virginia 
SIX PLATES (twenty-one FIGURES) 
The observations presented in this paper are selected from 
many that have been recorded by members of the staff of this 
laboratory. Some of the observations were taken from speci- 
mens in Petri dishes, some in uncovered drops, still others under 
cover-glasses, while many were secured from amebas that had 
been kept in hanging drops until time was available for making 
observations. 
We have found Ameba proteus reacting to two types of food. 
The first type embraces the following forms: desmids, Mouge- 
otia, quiet Oscillatoria, encysted Chlamydomonas, and bacterial 
gleas; while the second group of food bodies comprises flagellates 
like Chilomonas, Peridinium, and Euglena, ciliates like Parame- 
cium caudatum, Colpidium, Cyclidium, and rotifers. The first 
of these groups of food objects is characterized by being non- 
motile, the second group by being motile. Some of the non- 
motile objects give off oxygen, while others give off carbon diox- 
ide. The same may be said of the motile group; it, too, may be 
subdivided into the forms that give off oxygen and those that 
yield carbon dioxide to the surrounding medium. Therefore the 
most conspicuous difference between these two groups of food 
is the non-motility of the first group and the motility of the sec- 
ond group. 
Correlated with this conspicuous difference between the two 
types of food of Ameba there is a two-fold food reaction on the 
part of these rhizopods. Ameba's conduct toward non-motile 
food is much less complex than its conduct toward motile food. 
The less complex type of reaction is concerned with ingesting 
forms that do not set up currents in the surrounding water and 
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THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 32, NO. 3 
