570 ASA A. SCHAEFFER 



ber of times in succession. The same is true if a number of car- 

 mine grains are presented in succession, each grain being pre- 

 sented only once. The change in behavior is not due to fatigue 

 of the food cup forming mechanism. 



The carmine grains are egested by the raptorial amebas be- 

 cause they are actually disagreeable, and not merely because 

 they are (presumably) indigestible. This is indicated by the 

 fact that the ameba starts to move away after ingestion so that 

 the carmine shall at once occupy a position in the posterior part 

 of the body. Generally the direction of movement after inges- 

 tion is the resultant of the tendency to resume movement in the 

 original direction and the tendency to move away so that the 

 carmine is at once in the posterior region. 



From the ameba's standpoint carmine induces ingestion more 

 readily than pieces of crustacean or annelid meat. The latter 

 substances are digestible as is shown in later experiments. Pure 

 carmine, or carmine mixed with but a slight amount of egg white, 

 induces ingestion more readily than carmine containing a con- 

 siderable amount of egg white, or than particles of nearly insol- 

 uble egg white. 



India ink. The stick form of India (or chinese) ink which was 

 used in these experiments is a mixture of several substances, the 

 chief of which are carbon, a gum that is added in its manufacture 

 to make the carbon particles stick to each other, and a substance 

 resembling lecithin that may be extracted with hot ether or chloro- 

 form. The heterogeneity of the india ink makes it an undesir- 

 able test substance, for it is impossible to tell which of the in- 

 gredients causes the changes in behavior which the ink produces. 

 For this reason only a few experiments were made in which this 

 substance was employed. One of these, made on an irregularly 

 moving ameba, is figured — 1627. There was at first some vacilla- 

 tion, neither positive nor negative behavior being observed. 

 Finally, however, the ameba moved toward the india ink, and 

 extended a pseudopod on either side of it. The pseudopods lifted 

 the ink up. The ameba then resumed its original direction of 

 motion and moved away, the ink being carried to the back of the 

 ameba, from which it rolled a few minutes later. Although there 



