568 ASA A. SCHAEFFER 



raised in a culture rich in diatoms, desmids and oscillaria. The 

 amebas in this culture were very seldom observed to eat a motion- 

 less object. A small grain of pure carmine, about twenty microns 

 in diameter, was agitated with a glass needle. It was promptly 

 ingested by means of a typical food cup at twelve o'clock. It 

 soon came to lie near a mass of empty diatom shells. At 1.53 

 two diatoms, experimentally agitated, were eaten. One escaped 

 at 1.57. At 2.07 a diatom shell, with a small dark brown mass 

 inside, was actively excreted. At 2.37 no shrinkage of the soft 

 parts of the diatom eaten at 1.53 was observed. The diatom was 

 then lost from view. At 2.46 the ameba ate a desmid which was 

 mechanically agitated. At 3.11 an active Euglena viridis was 

 ingested. The euglena thrashed around in the endoplasai for 

 fifteen minutes, then it crawled out of the ameba as an earthworm 

 might wriggle out of a lump of soft clay. At 4.08 the desmid was 

 three-quarters liberated, and at 4.15 it was entirely freed. The 

 observations were terminated at 4.40, when the carmine grain 

 was still inside the ameba. The carmine had thus remained at 

 least four hours and forty minutes in the ameba. 



Thirteen days before the last experiment was performed, an- 

 other ameba from the same culture as the preceding was pre- 

 sented with a piece of globulin. It was partly enclosed then re- 

 jected. A piece of pure carmine was then eaten in the normal 

 manner with the formation of a food cup at 11.20. Then a flagel- 

 late was eaten. A fresh piece of globulin called forth a mild 

 positive reaction, then the ameba moved on over it without any 

 feeding reactions being called forth. At 3.15 another piece of 

 pure carmine was presented but it was not eaten. Several times 

 thereafter carmine was presented but in no case was any attempt 

 at ingestion observed. This ameba responded very readily to mild 

 stimulation with the needle. At one time three food cups were 

 formed at the same time over two oscillaria threads lying near 

 each other, and over a motionless but living Phacus triqueter, 

 which I mechanically agitated. The food cup over the phacus 

 was almost completed down to the glass, when agitation of the 

 phacus was stopped. The food cup was then retracted although 

 the phacus was still inside. The observations were terminated 



