56 K. S. LASHLET 



the necessity for any specialized structures and, indeed, consider 

 all learning, even of the conditioned reflex type, to be an inherent 



V function of protoplasm. This view has been advanced chiefly 

 by Neo-Lamarckians beginning with Bering and Butler and 

 extending to Semon, Driesch, Rignano, and F. Darwin among 

 Decent writers. The great mass of evidence upon which their 

 contentions are based is without firm foundation, consisting as 

 it does of inferences drawn from evolutionary series, and the 

 few experimental facts which are adduced, such as the results 

 of Schroeder and Kammerer, lack verification. Even if estab- 

 lished they would not bear directly upon the relation of somatic 

 induction to learning. Nevertheless, the contention for the 

 possibility of extra-neural learning can not be dismissed 

 summarily upon the basis of established facts. The most 

 recent contribution toward a theory of extra-neural learning is 

 that of Kappers ('17) in which it is assumed that excitatory 

 processes are conducted through non-nervous tissue, directing 

 growth processes and nervous integration. The doctrine 

 (neurobiotaxis) seems to have been received favorably by many 

 neurologists. It is, however, based wholly upon deductions from 

 anatomical data. Nowhere in the studies of growth or evolution 

 has a case of learning been actually observed. 



Have we any evidence that learning in the individual is pos- 

 sible in the absence of differentiated conduction paths? A few 

 years ago one might have been tempted to say that a demon- 

 stration of learning in protista would give a positive answer to 

 this question. But the recent publications of Sharp ('14), 



l_Yocom ('18), Taylor ('19) and others suggest that protista 

 have well differentiated conduction systems. Even in Amoeba, 

 in which there is no indication of structural differentiations of 

 this character, the observations of Kepner and Taliaferro ('13) 

 show that reactions may occur at a point far distant from the 

 point of stimulation, as when stimulation between two pseudo- 

 pods results in change in direction of movement at their tips. 

 So, while some observations, particularly those of Metalnikow 

 ('12), indicate that the protozoa are capable of forming habits, 

 we must conclude that there is no known case of learning in 



