2OO THE BEHAVIOR OF LOWKK ORGANISMS. 



tail. They progressed in this fashion for a long distance, many times 

 their own length. I watched them thus for more than 10 minutes. 

 The smaller, anterior specimen frequently altered its course ; the 

 posterior one followed. I stimulated the anterior end of the small 

 specimen with the tip of a glass rod (Fig. 75, 3) ; it turned at a right 

 angle, and the posterior specimen followed. After about 12 minutes it 

 could be seen that the smaller specimen was moving slightly faster 

 than the other and was slowly withdrawing its posterior end. Finally 

 it pulled completely away from the large Amoeba, which was still fol- 

 lowing as rapidly as possible. After the small Amoeba had completely 

 escaped the large one stopped and remained entirely quiet for a few 

 seconds. The large cavity in its anterior portion, which it had pre- 

 pared for the reception of the small Amoeba, and which extended 

 back behind the middle of the body, was still very evident. After a 

 time the Amoeba began to change form and sent out pseudopodia 

 irregularly in all directions. The smaller Amoeba continued its for- 

 ward locomotion as long as observed. The performance is illustrated 

 in Fig. 75, from sketches made while it was in progress. 



(2) In a second case I was able to observe the beginning as well as 

 the end of this microscopical drama (Fig. 76). I had attempted to 

 cut an Amoeba in two with the tip of a glass rod, in the manner described 

 later. The posterior third of the Amoeba, in the form of a wrinkled 

 ball, remained attached to the body only by a slender cord, the remains 

 of the ectosarc. The Amoeba began to creep away, dragging with it 

 this ball. I will call this Amoeba , while the ball will be designated b. 

 A larger Amoeba (c) approached, moving at right angles to the path 

 of the first Amoeba ; its course accidentally brought it into contact 

 with the ball , which was dragging past its front. Amoeba c there- 

 upon turned, followed Amoeba , and began to engulf the ball b. A 

 large cavity was formed in the anterior end of Amoeba c, reaching back 

 nearly or quite to its middle, and much more than sufficient to contain 

 the ball b. Amoeba a now turned into a new path ; Amoeba c followed 

 (Fig. 76 at 4). After the pursuit had lasted for some time the ball b 

 had become completely enveloped by Amoeba c; the cord connecting 

 it with Amoeba a broke, and the latter went on its way (at 5) and dis- 

 appears from our account. Now the anterior opening of the cavity in 

 Amoeba c became partly closed, leaving a slender canal (5) . The ball b 

 was thus completely inclosed, together with a quantity of water. 

 There was no union or adhesion of the protoplasm of b and c; on the 

 contrary (as the sequel will show clearly) both remained quite sepa- 

 rate, c merely inclosing b. 



Now the large Amoeba c stopped, then began to move in another 

 direction (Fig. 76, 5-6), carrying with it its meal. But the meal, the 



