322 SIGNIFICANCE OF SEXUAL REPRODUCTION [V. 



dividing the spinal cord, although the disease also resulted 

 from a transverse section through half of the latter organ, or 

 from the section of its anterior or posterior columns alone, 

 or from simply puncturing its substance. The most striking 

 effects appeared to follow when the spinal cord was injured 

 in the region between the eighth dorsal and the second lumbar 

 vertebrae, although the results were sometimes also produced 

 by the injury of other parts. Epilepsy also followed the division 

 of the sciatic nerve, the internal popliteal, and the posterior 

 roots of all nerves which pass to the legs. The disease never 

 appears at once, but only after the lapse of some days or weeks, 

 and, according to Brown-Sequard, it is impossible to conclude 

 that the disease will not follow the operation until after six or 

 eight weeks have passed without an epileptic attack. Ober- 

 steiner did not witness in any case the first sj^mptoms of the 

 disease for several days after the division of the sciatic nerve. 

 After the operation, sensibility decreases over a certain area 

 on the head and neck, on the same side as the injury. If the 

 animal be pinched in this region (which is called the epileptic 

 area, 'zone epileptogene ') it curves itself round towards the 

 injured side, and violent scratching movements are made with 

 the hind leg of the same side. After the lapse of several days 

 or even weeks, these scratching movements which result from 

 pinching in the above-mentioned area, form the beginning of 

 a complete epileptic attack. Hence the changes immediately 

 produced by the division of a nerve are obviously not the direct 

 cause of epilepsy, but they only form the beginning of a patho- 

 logical process which is conducted in a centripetal direction 

 from the nerve to some centre which is apparently situated in 

 the pons and medulla oblongata, although, according to others^, 

 it is placed in the cortex of the cerebrum. NothnageP con- 

 siders that certain changes, the nature of which is still entirely 

 unknown, but which may be histological or perhaps solely 

 molecular in character, must be produced, leading to an in- 

 creased irritability of the grey matter of the centres concerned. 



^ Compare Unvericht, ' Experimentelle und klinische Untersuchungen 

 liber die Epilepsie.' Berlin, 1883, With regard to the question of 

 hereditary transmission, the part of the brain in which the epileptic 

 centre is placed is of no importance. 



^ Compare Ziemssen's ' Handbuch der spec. Pathologie und Therapie.' 

 Bd. XII. 2. Halfte; Artikel * Epilepsie und Eklampsie.' Leipzig, 1877. 



