The Livhuj Machine 303 



the meal, the ball b, now began to show signs of life, sent out 

 pseudopodia, and indeed, became very active. \Ve shall 

 henceforth, therefore, speak of it as Amu?ba b. It began to 

 creep out through the still open canal, sending forth its 

 psetidopodia to the outside (7). Thereupon Am(eba c sent 

 forth its pseudopodia in the same direction, and after creeping 

 in that direction several times its own length, again c()ni|)l('tely 

 inclosed b (7-8). The latter again partly escaped (D), and 

 was again engulfed completely (30). Amoeba c now started 

 again in the opposite direction (11), whereupon Amieba b, 

 by a few rapid movements, escaped entirely from tlie posterior 

 end of c, and was free, being completely separated from e 

 (11-12). Thereupon c reversed its course (12), crept up to 

 b, engulfed it completely again (13), and started away. 

 Amoeba b now contracted into a ball, its protoplasm clearly 

 set off from the protoplasm of its captor, and remained quiet 

 for a time. Apparently the drama w^as over. Amoeba c went 

 on its way for about five minutes, without any sign of life in b. 

 In the movements of the Amoeba c the ball b gradually became 

 transferred to the posterior end of c, until finally there was 

 only a thin layer between b and the outer water. Now b 

 began to move again, sent out pseudopodia to the outside 

 through the thin wall, and then passed botlily out into the 

 water (14) . This time Amoeba c did not return and recapture 

 b. The two Amoebae moved in different directions and re- 

 mained completely separated. The whole performance occu- 

 pied, I should judge, about 12 to 15 minutes (the time was 

 not taken till several minutes after the beginning) . 



"After working with simple stimuli and getting always 

 direct simple responses, so that one begins to feel that he 

 understands the behavior of the animal, it is somewhat 

 bewildering to become a spectator of so striking and com- 

 plicated a drama. . . . The action is remarkably like that of 

 a higher animal. Doubtless we must assume chemical and 

 mechanical stimuli as directives for each of the movements 

 of c, but the analysis so obtained seems not very complete 

 or satisfactory. " ^ 



Injurious chemicals cause Amoeba to withdraw from them. 

 Similarly, if the water on one side of an Aiiueba be warmed, 

 the animal will contract on that side, and thrusting forth its 

 pseudopodia on the other side, move in the opposite direction. 

 If a weak electric current be passed through the water con- 

 taining Amoeba, its behavior is similar to that under a heat 

 stimulus. The side toward the anode or positive pole con- 

 tracts, while from the opposite side pseudopodia are extended, 



^Jennings, "Contributions to the Study of the Behavior of Lower 

 Organisms," Carnegie Institution, Publication No. 16. 



