234 THE BEHAVIOR OF LOWER ORGANISMS. 



(26) From (i) and (10) above it results that the simple locomotion 

 on a substratum could, taken by itself, be accounted for on Berthold's 

 theory that the movement is due to the spreading out of a fluid on a 

 solid. But this theory fails when we take into account the formation 

 of free pseudopodia (p. 214), and the fact that all the processes con- 

 cerned in locomotion can be performed without adherence to a solid 

 (paragraph (9) above). 



(27) From (3), (4), (9), (n), (12), (24), (25), (26), we must con- 

 clude that the formation of pseudopodia and the sending out of waves 

 of protoplasm at the anterior end of a moving Amoeba are due to a 

 local activity of the protoplasm for which no physical explanation has 

 been given. Since these are the essential features in locomotion, we 

 must conclude that locomotion in Amoeba has not been physically 

 explained. 



(28) From (17), (19), (20), it follows that we cannot, with fidelity 

 to the results of physical experimentation, hold that the effects of stimuli 

 in modifying the movements of Amoeba are due to their direct (or even 

 indirect) action in changing the surface tension of the parts affected. 



(29) From (21) we must conclude that adherence between the proto- 

 plasm and the food substance does not furnish an adequate explanation 

 of food-taking and the choice of food in Amoeba. 



(30) From (24), (25), (27), (28), we must conclude that changes in 

 the surface tension of the body are not the primary factors in the move- 

 ments and reactions of Amoeba. (See note, p. 225). 



(31) All the results taken together lead to the conclusion that neither 

 the usual movements nor the reactions of Amoeba have as yet been 

 resolved into known physical factors. There is the same unbridged 

 gap between the physical effect of the stimulus and the reaction of the 

 organism that we find in higher animals. 



(32) In the behavior of Amoeba we may distinguish factors compar- 

 able to the habits, reflexes, and automatic activities (Ziehen) of higher 

 organisms (pp. 228-229). Its reactions as a rule are adaptive (pp. 

 227-228). 



