76 A. A. SCHAEFFER 



The ameba moved directly forward toward it a short distance, 

 then turned to the left. Several pseudopods were sent out on 

 the right but all of them were soon withdrawn. Finally the tip 

 of the ameba turned strongly to the right and through it the 

 ameba moved away. The same grain of ovalbumin was again 

 placed in the path of the ameba (2072). The ameba moved 

 partly past it on the right. A food cup was then formed and the 

 ovalbumin ingested. About six minutes after the formation of 

 the food cup the ovalbumin was left behind. 



A fresh grain of ovalbumin was laid in the path of another 

 granular ameba (2082). The ameba moved forward a short dis- 

 tance, then broke up into two pseudopods of which the one 

 nearer the ovalbumin became the main pseudopod. As the 

 ameba moved forward, a side pseudopod was thrown out on the 

 right. This pseudopod formed the left hmb carrying the ameba 

 away. There was again a slight tendency to encircle the oval- 

 buiTiin. 



Ovalbumin seems to stand between lactalbumin and zein in 

 its power to stimulate the feeding reaction. In contrast to zein, 

 ovalbumin provokes ingestion frequently, but not so frequently 

 as lactalbumin. Ovalbumin also is sensed at a greater distance 

 than zein — about 100 microns. The digestibility of ovalbumin 

 was not tested. 



EXPERIMENTS WITH KERATIN 



This albuminoid was of Merck's manufacture. When freed 

 from fats and other proteins keratin is insoluble in w^ater although 

 it swells up shghtly. A grain of keratin was placed directly 

 ahead of a granular ameba (631). The ameba moved forward 

 into contact with it and partly surrounded it, but the ameba 

 kept on flowing in the original direction, and in a few minutes 

 the keratin was left behind. A new piece of keratin was then 

 laid near the ameba (640). The ameba moved forward toward 

 the keratin and when nearly in contact with it, broke up into 

 two pseudopods, both of which advanced toward the keratin un- 

 til they came into contact with it. The left pseudopod then 

 enlarged the more rapidly and moved on, leaving the keratin 



