CURRENTS CAUSED BY AMCEB^ 317 



weight. It is well known that R Hertwig succeeded in 

 rendering probable the existence of such an axial thread 

 for some Radiolaria also. 



As has been remarked, however, I regard it as still pre- 

 mature at present to think of a final explanation for the 

 formation of the fine pseudopodia, for we cannot, unfor- 

 tunately, say even for a moment that we have obtained a 

 satisfactory conception of the relations between their struc- 

 ture and movement, which must, however, be indispensably 

 the preliminary stage of any explanation. Hence, however 

 convinced I may be of the fact that to the explanation 

 attempted by me of the protoplasmic movements of Amcebcc, 

 etc., there attaches a further and essential significance for 

 the processes of movement exhibited by protoplasm gener- 

 ally, I am equally convinced, on the other hand, that it 

 would be very difficult to work out the explanation of the 

 numerous special cases which exist on the basis of that 

 principle at the present time, or at any rate that their 

 explanation could only be achieved by the help of numerous 

 subordinate hypotheses, which would considerably diminish 

 the probability of the explanation. I therefore consider it 

 not worth while to pursue this uncertain path with earnestness, 

 but hope that with a renewed study of the processes of 

 movement, which we shall probably not have to await very 

 long, in connection with the ideas put forward here as to the 

 probable causes of those processes, more sure foundations of 

 fact may be discovered for the solution of these questions. 



On the Currents in the Water surrounding Anwbce, etc. 1 



I have already expressed my regret that I did not earlier 

 test the important question as to the existence of currents 

 in the water surrounding a moving Amoeba. Having recently 

 had an opportunity in an object so excellent for this purpose 

 as Pelomyxa, I must say that the ordinary small Amcebce offer 

 very little occasion for the solution of this question. Now 

 although during frequent observation of the processes of move- 

 ment in Pelomyxa I invariably was astonished by the per- 

 fectly complete agreement of its movements, even in detail, 



1 An addition made by the author in April 1892. 



