REACTIONS OF AMEBA TO PROTEINS 65 



EXPERIMENTS WITH GLUTEN 



This substance was purchased from Eimer and Amend. Its 

 purity was not investigated. It is probable that several proteins 

 are included under the term gluten. The particles of gluten, 

 when immersed in water, showed a brownish tint under the mi- 

 croscope, while those of globulin were a Ught straw yellow. The 

 results of the experiments with this substance are in most respects 

 similar to those in which globuUn was used. 



The attractiveness of grain gluten as compared with globulin is 

 well shown in the following experiment. A grain of gluten was 

 placed in the path of a granular ameba (326) . The ameba moved 

 on into contact with the gluten and then on under it. Presently 

 the gluten rolled off the ameba's back. The ameba then sur- 

 rounded it without forming a food cup. The eating process sug- 

 gested only mild attraction toward the gluten. Four minutes 

 after ingesting the gluten the ameba moved off in the original 

 direction. A small ameba of another species that happened to 

 be near, attracted the ameba slightly, but it finally turned to the 

 right and avoided the small ameba. Another grain of gluten 

 that was now placed in the ameba's path was avoided at first 

 but attracted the ameba later. It was nevertheless finally left 

 behind as the ameba moved away. The gluten grain was placed 

 in the ameba's path again but was passed by without ingesting it. 

 The gluten was laid in the ameba's path for the third time but 

 it was passed over mth seeming indifference. Next a grain of 

 globuhn (366) was eaten. A fresh piece of globuhn placed before 

 it was also ingested. A third piece of globuhn remained unno- 

 ticed (381). But when this piece of globuhn was placed near 

 the ameba it was promptly ingested (383). 



Globulin evidently attracted this ameba considerably more 

 strongly than gluten did, three pieces of globulin having been 

 eaten to one of gluten. Moreover the gluten grain was not 

 eaten with readiness but with indifference; while globulin was 

 eaten as if the ameba was very hungry. In the five tests with 

 gluten to which the ameba was subjected, behavior became more 

 and more indifferent with each succeeding trial. It is hkely that 

 the habit of behaving indifferently, or negatively, to the gluten 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 22, NO. 1 



