REACTIONS OF AMEBA TO PROTEINS 69 



ment was pointed out when the ingestion of hving organisms was 

 discussed in a previous paper (On the feeding habits of ameba, 

 Jour. Exp. Zool., vol. 20, 1916). This point will be discussed 

 again from another point of view in a later paper. 



Although movement seems to be necessary in an object in 

 order to insure its being eaten, yet movement is unnecessary to 

 attract a raptorial ameba from a distance; and in exceptional 

 cases movement seems to be unnecessary even to successful 

 eating. The changes in ameba which give rise to these cases of 

 exceptional behavior are not understood, owing to the small num- 

 ber of recorded experiments. 



EXPERIMENTS WITH ALEURONAT 



This is a commercial product and consists of several substances 

 in intimate mixture. It is sometimes used in the dressing of 

 wounds on account of its so-called chemotactic action on leuco- 

 cytes. The greater part of aleuronat consists of proteins. The 

 food qualities of aleuronat are similar to those of the other insolu- 

 ble proteins mentioned above, as the following experiment will 

 indicate. 



In the path of a granular ameba was placed a grain of aluero- 

 nat (1372). The ameba moved directly forward and as it neared 

 the aleuronat it spread out. Two pseudopods were then sent 

 out at the edges of the main pseudopod, which finally enclosed 

 the test substance in an imperfect food cup. The aleuronat 

 was completely ingested. One and one-half minutes later the 

 ameba resumed its previous direction of movement. The ameba 

 reacted toward aleuronat as it does toward globulin or any 

 other hfeless food body. But the stimulating power of alueronat 

 does not seem to be intense, for no food cup was formed. As 

 compared with a piece of egg white, fed ten and one-half minutes 

 later, which was ingested with a large food cup, aleuronat seems 

 to possess only mild food properties. 



Granular amebas eat aleuronat but not with the same readiness 

 with which gluten and globulin are eaten. In other respects it 

 calls forth about the same behavior as these substances. Rap- 

 torial amebas do not eat aleuronat. In some cases ingestion is 



