THE MOVEMENTS AND REACTIONS OF AMCEBA. 197 



thereupon altered its course so as to follow the cyst (Fig. 73 *) The 

 cyst was shoved forward again and again, a little to the left; the 

 Amoeba continued to follow. This continued until the two had tra- 

 versed about one-fourth the circumference of a circle ; then (at 3) the 

 cyst, when pushed forward, rolled to the left quite out of contact with the 

 Amoeba. The latter then continued forward with broad anterior edge 

 in a direction which would have taken it past the cyst. But a small 

 pseudopodium on its left side came in contact with the cyst. The 

 Amoeba thereupon turned again and followed the rolling cyst. At 

 times it sent out two pseudopodia, one on each side of the cyst (as at 

 4), as if trying to inclose the latter, but the ball-like cyst rolled so easily 

 that this did not succeed. At other times a single very long, slender 

 pseudopodium was sent out, only the tip of which remained in contact 

 with the cyst (5). Then the body of the Amoeba was brought up from 

 the rear and the cyst pushed farther. This continued until the rolling 

 cyst and the following Amoeba had described almost a complete circle, 

 returning nearly to the point where the Amoeba had first come in con- 

 tact with the cyst. At this point, owing to the form of the anterior 

 end of the Amoeba (7) the cyst rolled to the right instead of to the left 

 as it was pushed forward. The Amoeba followed (8, 9). This new 

 path was continued for two or three times the length of the Amoeba. 

 The direction in which the ball was rolling would soon have brought 

 it against an impediment, and I thought it possible that the Amoeba 

 might succeed in ingesting it after all. But at this point one of those 

 troublesome disturbers of the peace in microscopic work, a ciliate infu- 

 sorian, came near and whisked the ball away in its ciliary current. 

 After the ball was carried away the Amoeba continued to follow in the 

 same direction for only a very short distance, about one-fifth its length, 

 then reversed its course and went elsewhere. 



The movements of Amoeba are, of course, very slow, and the behavior 

 described required a considerable period of time 10 or 15 minutes, I 

 should judge. The whole scene made really an extraordinary impres- 

 sion on the observer, and it is difficult in describing it to refrain from 

 the use of words that imply a great deal of resemblance between Amoeba 

 and immensely higher organisms. One seems to see that the Amoeba is 

 trying to obtain this cyst for food, that it puts forth efforts to accom- 

 plish this in various ways, and that it shows remarkable pertinacity 

 in continuing its attempts to ingest the food when it meets with diffi- 

 culty. Indeed, the scene could be described in a much more vivid 

 and interesting way by the use of terms still more anthromorphic in 

 tendency. 



I have seen a large number of cases like that above described ; in 

 some of my cultures containing many specimens of Amoeba proteus 



