REACTIONS OF AMEBA TO PROTEINS 75 



EXPERIMENTS WITH ZEIN 



By reason of the fact that this protein is soluble in 95 per cent 

 alcohol, it may be obtained in a state of great purity. Zein is 

 insoluble in water. This is one of the purest proteins obtainable. 



In the path of a granular ameba which had previously eaten 

 two grains of globulin but which was unable to retain lactalbu- 

 min, although several pieces had been ingested, was placed a grain 

 of zein (833) . While the ameba was moving forward toward the 

 zein, a pseudopod was formed on the right through which the 

 ameba moved off. A fresh grain of zein was then placed ahead 

 of the ameba (836). The ameba moved forward into contact with 

 it and then pushed it about for awhile. A third grain of zein 

 was then placed in the ameba's path (843). The ameba flowed 

 into contact with it and then rolled it about for a while. At one 

 time it seemed as if ingestion were about to occur (850, 851) ; 

 the zein was partly surrounded but the protoplasm was soon 

 withdrawn from it, and the ameba moved on, leaving the zein 

 behind. 



In the path of a granular ameba from the same culture as 

 the preceding, after reacting as recorded in figures 854 to 911, was 

 laid a grain of zein. The ameba moved off in another direction, 

 no attempt being made to ingest it. 



Zein does not seem to be sensed at a greater distance than sixty 

 microns. The short range at which this substance may be 

 sensed is possibly due to its freedom from soluble impurities. 

 In none of the experiments was there any certain attempt at 

 ingestion, although in several cases the zein was rolled around 

 for awhile. As a stimulator of the feeding mechanism zein 

 stands far below lactalbumin. xA.s will be- seen later, zein really 

 stands at the bottom of the list of all isolated proteins in this 

 respect. It seems to have no more power to induce feeding 

 than particles of sand. 



EXPERIMENTS WITH OVALBUMIN 



The ovalbumin was coagulated in the process of preparation 

 to render it insoluble. 



In the path of a granular ameba that had previously ingested a 

 piece of globuHn was laid a piece of ovalbumin (not figured). 



