474 



MESSES. F. GOTCH AND V. HORSLEY 



In these experiments, it is seen that the right lateral column was excluded from 

 the section, and that stimulation of no other column above the section, except the right 

 lateral, produced any nerve effect. 



It has, however, been shown in Chapter IX. that when impulses proceed up the 

 posterior roots into the cord they are conveyed to some extent (20 per cent.) by the 

 lateral columns of the same side. A connection between the posterior root fibres and 

 the lateral column, presumably by means of fibres in the posterior column or cornu, 

 must therefore exist. This connection is, however, of such a special kind that it 

 offers an evident resistance to the passage of impulses backwards from the cord into 

 the root. The fact that no effects in the above experiment could be obtained when, 

 with the lateral column as the sole bridge between the excited upper portion of 

 the cord and the nerves, the posterior columns were excited, shows that any spread 

 of path from the posterior to the lateral columns, if it exists, must either be below 

 the level of the section (12th dorsal) or must offer a resistance to the passage of 

 impulses in the downward direction which it does not offer to their passage in the 

 upward direction, that is, in their ascent towards higher centres. 



The relations which the cord columns appear to have with one another, as given in 

 the summary of Chapter VIII., are in this respect of great interest and importance. 



Two results are clearly brought out by the consideration of the series of experiments 

 in the whole of this section ; the first that the analogous character of the general 

 electrical results in cord and nerve, without being pushed too far, may be extended to 

 this point, that the stimulation of any one column in the cord is a localised stimulation 

 of the nerve fibres in that column only, and the second, that the resulting nerve 



