1892.] On the Brachial Plexus of the Dog. 23 



generalised epileptic spasm induced in the limb by cortical excita- 

 tion. 



6. Differentiation of parts of the nerve roots by the degeneration 

 method, in which connexion an allusion is made to certain results 

 obtained by the author, which do not accord with the Wallerian law 

 of degeneration, and which are in accord with the experiments of 

 Joseph. 



From the results of these various methods of experimentation, the 

 author draws the following conclusions : — 



I. Stimulation Experiments. 



1. The compound movement obtained by stimulation of a whole 

 nerve root is a well-coordinated one, depending on the action of a 

 group of muscles in synergic combination, as Ferrier and Yeo showed 

 to be the case in the monkey. 



2. This compound effect may be resolved into its component factors 

 when it is found that movements diametrically opposed to each other 

 may be represented in the same nerve root, e.g., flexion and extension. 



3. Such single simple movements bear a constant relation to the 

 nerve roots, the same movements being always found in any given 

 root, and thus such movements always bear the same relation to the 

 spinal level ; e.g., flexion of the elbow is always represented one root 

 higher than extension of the same joint. 



4. Fibres representing a certain movement always preserve the 

 same position in a given nerve root ; e.g., extension of the wrist is 

 represented by a bundle of fibres in the upper part of the circum- 

 ference, while flexion is represented by a bundle of fibres in the lower 

 part of the same root. 



5. Each bundle of nerve fibres representing a single simple move- 

 ment in a nerve root remains distinct in its course to the muscle or 

 muscles producing such a movement, without inosculating with other 

 motor nerve fibres. 



6. The group of muscles supplied by any given nerve root occupy 

 both the anterior and posterior surfaces of the limb. In other words, 

 muscles whose unimpeded action would produce one movement are 

 represented in the same root as others whose action would produce a 

 movement diametrically opposite. 



7. In such combinations certain muscles are always more exten- 

 sively represented than others, so that, with a current sufficiently 

 strong to stimulate all the fibres of a nerve root equally, certain 

 muscles predominate in their action over others. 



8. The muscles whose action predominates in one root always pre- 

 dominate in that root. 



9. If the muscles producing flexion of a certain joint predominate 



