380 



MESSRS. F. GOTCH AND V. HORSLEY 



excited where it had been exposed in the dorsal cross section, the excitation being as 

 in the preceding case, viz., that of the interrupted induction currents (100 per second) 

 with the Helmholtz side-wire, and the period of excitation being 3^ seconds. 



As in the Cat, the excitation of either anterior column produced no effect ; that of 

 each lateral, however, evoked a marked electrical effect, the two laterals giving 

 respectively, left 75 and right 62, the deflection being in each case opposed in 

 direction to that of the resting difference. Excitation of either posterior column 

 was followed by a much smaller deflection than the corresponding lateral, the left 

 giving 34, the right 40. 



Fig 13 



When a stimulus of double the strength (coil 1000) but of the same duration was 

 employed, very large deflections were produced, but the relationship of the results 

 still held good, as excitation of the left lateral gave 210, whilst that of the corre- 

 sponding posterior gave 165, and similarly excitation of the right lateral gave 140, 

 whilst that of the corresponding posterior gave 120. 



If the comparative value of the electrical change produced in the cord by " minimal " 

 excitation of the different columns be represented graphically, as in the annexed figure, 

 a glance is sufficient to show the striking contrast between the result obtained in the 

 Cat and that obtained in the Monkey, since in the latter case the laterals pre- 

 dominate over the posteriors. (See fig. 13.) 



