ON THE MAMMALIAN NERVOUS SYSTEM. 



515 



severed, and the lower fragment connected in the manner practised in all the 

 preceding experiments, and strychnia injected, very large electrical changes were 

 observed. These were produced in the upper, as well as the lower, end of the dorso- 

 lumbar portion of the cord. The maximal effects were over 500 scale of galvanometer, 

 and the average in one experiment of all the readings was as high as 300. 



To sum up these experiments with a chemical stimulus, from the point of view from 

 which they were designed, it is clear that the excitatory electromotive changes (i.e., 

 diminution in the resting difference) observed to occur in the central nervous system 

 when that is excited electrically or mechanically, are true indications of physiological 

 phenomena accompanying functional activity, and, further, that their amounts vary 

 directly in proportion with the intensity and duration of such activity. 



CHAPTER XIII. SUMMARY AND CONCLUSIONS. 



The consideration of the results given in the foregoing chapters shows, we venture to 

 think, that the electrical method of investigating the localisation of nerve impulses in 

 the Mammalian nervous system is one which has furnished several new aspects of nerve 

 function, and we believe that if further pursued it will prove one of the most valuable 

 means of differentiating the structure of the nervous system, and gauging the nature 

 of the functional activity of the nerve centres. 



In view of the extended scope of our present research, we feel unable to give a suffi- 

 ciently brief summary of the results. We therefore propose to enumerate, by way of 

 conclusion, some of the general principles which we think we are justified in deducing 

 from our work. 



The following remarks, therefore, cannot in any sense be regarded as embodying 

 the whole of our investigations, and we must consequently refer our readers to the 

 individual chapters, and especially to the remarks at the end of each, for information 

 as to points upon which we do not here touch. 



(1.) Resting Electrical Difference. 



The resting electrical difference between the cut and uninjured longitudinal 

 surface respectively in the Mammalian mixed nerve, spinal nerve root, and spinal 

 nerve, has been found by us to have the following value : 



3 u 2 



