ON THE MAMMALIAN NERVOUS SYSTEM. 



453 



RIGHT Nerve connected. 



Intensity of stimulus again doubled. 



LEFT Nerve connected. 



HIGHT Nerve connected. 



The above experiment shows plainly that, with a weak stimulus, an effect is only 

 produced in the nerve by stimulating the posterior columns, and that this effect is 

 very marked when the directly continuous fibres in the posterior column of the same 

 side as the observed nerve are excited, and is small when the fibies of the posterior 

 column of the opposite side are excited. A very small effect is produced by stimu- 

 lating the lateral columns until the stimulus is strong, and even then an appreciable 

 effect is obtained only from the excitation of the lateral on the same side as the nerve. 



A similar experiment may now be quoted in detail upon the Monkey (333) 

 (Macacus sinicus). The cord was divided in the anaesthetised animal at the 10th 

 dorsal vertebra, so that the cut ends of the various columns could be excited as in 



