BEHAVIOR OF AMEBA TOWARDS VARIOUS SUBSTANCES. 323 



After being in contact with the tube for a few minutes the ameba 

 moved away from it about 100 microns, but soon returned again. 

 The whole behavior is puzzling, and may have had no relation 

 to the diffusing albumin. 



A new tube of egg albumin was placed to the right of the path 

 of a raptorial ameba 405. As the ameba passed the opening 

 of the tube a pseudopod was thrown out on the side directly 

 toward the tube 407 but it was retracted when about twenty 

 microns from the tube 408. The ameba moved on without 

 further reaction. The tube was then shifted 410 but it was 

 definitely avoided by the ameba. When shifted again 415 

 it was again avoided. When shifted the third time 422 the 

 behavior was indifferent. 



Another tube of albumin solution was placed to the right of a 

 raptorial ameba 426. A pseudopod which was thrown out on 

 the right moved directly into contact with the open end of the 

 tube 432. From this pseudopod another was sent out which 

 moved along the side of the tube, and through it the ameba 

 moved off 433, 434. There was no attempt made to form a 

 food cup at any time. 



In the path of another raptorial ameba was placed a fresh tube 

 of albumin 436. This ameba was very strongly attracted by 

 the albumin, for five food cups (451, 452, 455, 466, 469) were 

 formed over the tube opening during the forty-one minutes the 

 ameba remained in contact with the open end of the tube. Only 

 the first food cup was completely closed; the others were only 

 partially formed. This is the only certain case where a food 

 cup was formed over the albumin because of stimulation proceed- 

 ing from the albumin. 



To summarize: The majority of amebas experimented upon 

 reacted with indifference, or negatively, to the egg albumin in 

 capillary tubes. Only one reacted decidedly positively, but this 

 one formed five food cups in succession over the open end of the 

 tube. There can be no doubt then of the efficiency of albumin 

 as a stimulator for setting off the feeding process ; nevertheless the 

 stimulus seems to be weak as compared with that from peptone. 



Tyrosin. A tube filled with weak tyrosin solution was placed 

 in the path of a raptorial ameba 398. A pair of side pseudopods 



