ON THE MAMMALIAN NERVOUS SYSTEM. 



475 



impulses generated at the seat of stimulus are propagated to the root of the nerves 

 along fibres constituting direct and indirect tracts, which are for the most part con- 

 fined to the particular column which has been excited ; the sole exception being that 

 of the posterior column on the opposite side to that from which the nerve roots 

 spring. 



SECTION 7. SUMMARY AND CONCLUSIONS. 



The experimental results detailed in this chapter form a sequel to those of the 

 preceding Chapter IX., as to the relations which exist between the lumbar nerves and 

 the spinal cord. Complete harmony between the results of the two series of experi- 

 ments is not to be expected from the very different physiological and anatomical 

 conditions which they involve. It will, however, be seen, if we compare the present 

 results with those given in the summary of Chapter IX., that as regards the main 

 points the one set form a corollary to the other. 



In order that the salient features of the two should be clearly expressed, the 

 following Table, in which all the results of the present chapter are massed under 

 different heads, is laid before the reader. 



The Table shows the average percentage of the total amount of the effect which 

 has been observed in the sciatic nerve, or its roots, when each lateral and posterior 

 column of the cut cord is respectively stimulated. 



The same average percentage is also shown, when the stimulus is minimal, in a 

 separate appended table. 



I. THE Amount per cent, of the Total Nerve Effect evoked by adequate Cord 

 Stimulation due to Localised Excitation of Particular Columns. 



II. THE same when the Cord Stimulation is Minimal. 



3 p 2 



