No. 453-] 



ACTIVITIES OF AMUIBA. 



641 



of the trophies of its prowess, — its supposed full cxiilanation of 



most of the activities of Amoeba,- and bearin,-- instead the 



record of a complete defeat. 



What positive results of value have the physi( ;d iinilaiions of 

 vital activities in Amoeba to show .^^ As we have seen, there are 

 still two or three of these that may really ,i;ive us a t hie to the 

 factors at work in the vital processes; at least this has n(»t yet 

 been disproved. Beyond this the i>ositive results aie oi a \cry 

 general character. The imitations .show that a drop ol fluid 

 might, through physical factors, show locomotion, move toward 

 certain agents and away from others, and exhibit choice in the 

 taking in of certain substances and the rejection of others. But 

 they do not show specifically through what physical fact(jrs the 

 activities are as a matter of fact brought about in Amoeba or any 

 other particular organism. 



The chief value of most of the attempted physical imitations 

 is that of a trial. The method of trial and error is a method of 

 progress in science as elsewhere. In these imitations a definite 

 explanation of the phenomena is put on trial. The " trial " con- 

 sists in a more careful study of the phenomena in question ; it 

 is as an inspiration to such study that the imitations are of great 

 value. If as a result the explanation given is recognized as 

 ^' error," that is in itself an advance; this particular trial will 

 not need to be made again. Continued application of this 

 method of trial and error must result finally either in the dis- 

 covery of the real factors at work, or in the recognition that we 

 are dealing with a new class of factors not found in physics. 



BIBLIOGRAPHY. 



Bernstein, J. 



1900. Chemotropische Bewegungen eines Quicksilbertropfens. Arch, 

 f. d. ges. Physiol, Bd. 80, pp. 62^-637. 

 BUTSCHLI, O. 



'90. Experimental Imitations of Protoplasmic Movement. Quart. 

 Joum. Micr. Sci., vol. 31, pp. 99" '°3- 



