Implications of the Theories of Nerve Action 187 



The Real Importance of Loch's Conception of the Xervous 



Si/ stem 



First of all, it is witli genuine satisfaction that I recognize 

 the eminent service rendered plivsiolocry aiid "-eneral hioloffv 

 by this author's experimental investigations on animal ac- 

 tivities. I have long considered that one of physiology's 

 foremost achievements is the clarification of the conception 

 that nerve phenomena, the most characteristic features of 

 which are response to stimuli and the conduction of the 

 effects of stimulation, are not wholly unique attributes of 

 nerve tissue, but are elaborations of attributes inherent in 

 all protoplasm. Perhaps no single pliysiologist has con- 

 tributed more to tliis clarification than has Loeb. Par- 

 ticularly important has been his demonstration tliat nerve 

 centers in the sense of ganglionic masses which determine 

 reflexes are not fundamental to the coordinated and adapted 

 movements of animals; that reflexes take place in manv 

 animals normally and in many others experimentally, where 

 no such centers exist, as for example in the ascidian after 

 the single ganglionic mass is cut out. 



The pertinacity and teclmical skill with which T.oeb has 

 followed up these ideas are highh' commendable. By focus- 

 sing attention on the fact that since plants have no nei-Aous 

 system, they are, in so far as they exhibit movement induced 

 by stimuli, illustrations of the principle of protoplasmic 

 response in actually differentiated organic beings ; and In- 

 carrying the same conception over Into the animal world and 

 demonstrating that many activities here also are dependent 

 upon direct protoplasnuc response and not necessarilv on 

 a specially differentiated ganglionic mass, he was led to 

 formulate the tropism theory. This theory, as we shall 

 show presently, has a significance which I^oeb himself seems 

 not to have fully comprehended, his general standpoint be- 

 ing unconductive to such comprehension. The theorv must. 



