314 A. A. SCHAEFFER. 



had passed beyond the starch 298 two side pseudopods were 

 thrown out toward the starch 299 the anterior one of which 

 came into contact with it 300. Both the side pseudopods were 

 retracted as the ameba started to flow away through the vestige 

 of a former pseudopod shown in Fig. 296 with the arrow. While 

 moving forward the ameba passed another mass of starch grains 

 without reaction. A grain of globulin was then ingested but 

 was excreted a few minutes later. 



Arrowroot starch grains are sensed at a distance and usually 

 induce positive behavior. The reactions are more decidedly 

 positive than those induced by glass or carbon, but no attempt 

 at ingestion was observed. A number of experiments with corn- 

 starch produced essentially the same results as those with arrow- 

 root starch. 



Lead Oxide. Eimer and Amend's Pure Yellow Lead Oxide. 

 A raptorial ameba was isolated and a small mass of lead oxide 

 placed in its path 473. As the ameba moved forward it turned 

 toward the oxide 475, 476 showing that this material may be 

 sensed at a distance of at least forty microns. After the ameba 

 came into contact with the oxide a small pseudopod was thrown 

 out posterior to it 479. The oxide was partially surrounded 

 and the behavior suggested the first stage of ingestion, but the 

 ameba moved on leaving the oxide finally behind 484. A new 

 mass of oxide was then placed before the ameba 485. The 

 ameba moved directly forward into contact with the oxide, and 

 there was observed again what seemed like the initial stages of 

 ingestion 487. The ameba then broke up into several pseudo- 

 pods 488. A food cup was formed between the two pseudopods 

 on the left, but nothing could be observed in it. It is probable 

 that the presence of the lead oxide was the cause of the formation 

 of the empty food cup. The ameba finally moved on leaving 

 the oxide behind. A piece of globulin which was then laid 

 before the ameba remained uningested perhaps because of the 

 just previous disagreeable effect of the lead oxide. Several 

 essentially similar instances are recorded in my previous papers 

 cited above. A new mass of lead oxide was then placed in the 

 path of another granular ameba 491. The ameba moved for- 

 ward a short distance then turned to the right 492. The 



