296 Journal of Comparative Neurology. 



segmental, or segmental plus suprasegmental ; (2) a definite 

 vegetative condition and definite functional connections of all 

 the elements concerned ; and (3) definite groups of efferent ele- 

 ments. 



This consideration shows us that a reaction is not to be 

 compared to a piece of meat put into one end of a sausage 

 machine and coming out as a sausage at the other ; nor is it 

 best to compare the process with a current ; it is more correct 

 to say that a chain or complex of nerve-elements gets into a 

 state of coordinated activity ; one element after the other takes 

 up the state of * tension ' and the cooperation of the whole chain 

 represents the neural activity in any reaction. It is a wave of 

 agitation or of action passing over very heterogeneous material, 

 involving some elements but not others. Or if we take the 

 simile of a current we must realize that each link has its state of 

 action for itself, each cell perhaps in all its branches, and it does 

 not get the action from another cell but merely the impulse. 

 This seems perhaps a mere speculation. I do not hesitate to call 

 it so ; the ordinary reflex-diagram, however, is also speculation, 

 evidently less ' hampered ' by facts, although we see it so often 

 that we acquiesce to it as a ' fact.' 



This concept of interaction of nerve-elements and the for- 

 mation of systematic acts, etc., is in full harmony with the 

 concept of the neurone. It considers many kinds of neurones 

 with many interrelations, each with its value as a cell and yet 

 part of the whole organism, capable of entering into many 

 chains of neural activity. Experimentally these chains can be 

 followed as Horsley and Gotch have done for electric stimula- 

 tion, or perhaps by poisoning certain definite mechanisms, etc. 

 But only a combination of all neurological methods will help us 

 to arrive at more clearness. In the mean time the above plan 

 would seem to furnish a fair working hypothesis. 



In clinical neuropathology, the chains of neural activity 

 become accessible to observation in two ways : (i) The con- 

 traction of voluntary and involuntary muscles, (and perhaps 

 also of other tissues, in the retina, etc.?) and (2) the subjective 

 mental side of the process. We observe objectively, as it were, 



