No. 453-] 



ACTIVITIES OF AMCEBA. 



If, then, the movements of Amoeba are really produced as 

 they are in the imitations, by means of local changes in surface 

 tension, we must expect to find in Amoeba these characteristic 

 currents. In an Amoeba moving in a certain direction there 

 should be a central current forward and superficial currents 

 backward. In an extending pseudopodium the central current 

 should be toward the point, the superficial currents away from 

 it. Do such currents exist ? 



There is evidently a central cur 

 superficial currents backward, as 

 studying the movements from 

 above, without the aid of experi- 

 ment, it is difhcult to determine 

 this point. But there are certain 

 appearances on the lower surface 

 and at the lateral margins which 

 give the impression that such back- 

 ward currents may exist. In fact 

 Butschli, Rhumbler and others be- 

 came convinced of the existence 

 of such currents. The movements 

 of Amoeba were thus brought into 

 full agreement with those of the 

 drops moving as a result of local 

 decrease in surface tension. This 

 is brought out clearly by an exam- 

 ination of the figures of the cur- 

 rents in Amoeba given by Butschli 

 and Rhumbler, copied in Figure 2. 

 It was then almost inevitable to 

 conclude that the same causes are 

 that the movements of Amaba are 



ntal 



In the extended experin 

 Amoeba recently made by the pres 

 shown that the supposed backward c 

 not exist. On the contrary, all i)arts 

 not attached to the substratum arc tv] 



(,f the 



