CHOICE OF FOOD IN AMEBA 223 



globulin were laid close together in the path of an A. proteus — 

 67. As the ameba moved forward a pseudopod was thrown out 

 on the left toward the globulin-hematin. A food cup was formed 

 and both substances were ingested. There was no period of 

 rest, the ameba moving on in the same direction. The hematin 

 remained in the ameba's body for a considerable time there- 

 after. A little later another grain of hematin and one of glob- 

 ulin were laid in the ameba's path — 78. The ameba moved 

 into contact with them and carried them up on its back — 82, 

 and then formed a food cup extending upwards and ingested 

 them. The ameba remained comparatively quiet for a short 

 period, then moved on in the original direction. Another grain 

 of hematin was then laid with a grain of globulin some distance 

 ahead of the ameba — 87. The ameba moved forward toward 

 the test objects and when within about seven microns of them — 

 91, 92 — the tip of the main pseudopod spread out and formed 

 a food cup over them just as if they were moving organisms 

 like flagellates. The food cup was completed and the hematin- 

 globulin taken into the protoplasm as on the two previous 

 occasions. The ameba quieted down for a few minutes, then 

 moved off about thirty degrees to the left of the original direction. 



No attempt was made by the ameba in any of these experi- 

 ments to separate the globulin from the hematin and to ingest 

 the globulin only, leaving the hematin behind. But it is to be 

 noted that in all these experiments the globulin grain was much 

 larger than the hematin. The most remarkable incident is the 

 ingestion in a food cup — 93, 94 — where the food cup was formed 

 before the ameba had come into actual physical contact with 

 the hematin or the globulin. 



Globulin and uric acid. — A large grain of globulin and a small 

 grain of uric acid were laid close together in the path of the 

 ameba used in the experiment with hematin and globulin recorded 

 above — 129. The ameba moved forward into contact with the 

 globulin-uric acid and ingested them without the formation of 

 a food cup. The ameba remained quiet for about five minutes, 

 after which it moved off in the original direction. 



Globulin and carbon. — A small grain of carbon was laid on a 

 larger grain of globulin in the path of an active A. proteus— 

 138. The ameba moved forward in Y-form with the carbon- 

 globulin lying between the prongs. The right prong finally 



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