REACTIONS OF AMEBA TO PROTEINS 73 



same dirction leaving the lactalbumin behind three and one-half 

 minutes after ingestion. The same piece of lactalbumin was then 

 presented again (823). The ameba moved forward into contact 

 with it, then followed it about for a while and finally left it behind. 



The general behavior of this ameba is striking in several ways. 

 Globulin is readily ingested to remain so, but lactalbumin is 

 invariably excreted after ingestion. Likewise keratin. After a 

 lactalbumin grain has been once ingested it is not ingested again, 

 although it may attract the ameba into following it abaut for 

 a while. If the ingested and excreted grain of lactalbumin is 

 presented several times in succession, each succeeding test calls 

 forth less change in behavior; but if followed by a fresh grain 

 ingestion may ensue. The decreasing attractiveness of the same 

 lactalbumin grain when presented several times in succession, 

 may be due to learning of a simple sort. This ameba is fairly 

 consistent in its general behavior. Figures 744 to 779 present be- 

 havior very similar to that recorded in figures 780 to 805. 



Another ameba from the same culture reacted to lactalbumin 

 in a different manner; several grains of it were completely in- 

 gested to remain in the body for a considerable time. The first 

 grain was ingested in a typical food cup (854). Ingestion was 

 not followed by a period of rest. After several pseudopods had 

 been thrown out and retracted, the ameba finally moved off in 

 the original direction. A fresh piece of lactalbumin was then 

 laid in the ameba's path (87). The ameba came into contact 

 with it at the side. The lactalbumin was ingested by the proto- 

 plasm flowing around it. There was again no period of rest 

 after eating the lactalbumin. The ameba moved off 30° to the 

 right, carrying the two pieces of lactalbumin at the extreme pos- 

 terior end of the body. A third piece of lactalbumin was then 

 laid in the path of the ameba (883). The ameba flowed directly 

 toward it and ingested it in an imperfect food cup. The ameba 

 moved off without a period of rest 60° to the left of its original 

 direction. This left the last grain of lactalbumin at once in the 

 posteroir end of the ameba. But the lactalbumin was not sub- 

 sequently excreted. A grain of globulin was then presented for 

 purposes of comparison (888). It was ingested in an imperfect 



