EniTouiAL, Neurology and Psychology. 1917 



second part of this article. The writer has endeavored 

 to show that consciousness in the limited sense is of compar- 

 atively late origin, and that a rigid application of the doc- 

 trine of natural selection would exclude it from all participa- 

 tion in nervous activities until such time as the struggle for 

 survival had become ameliorated to an extent, making con- 

 scious selection possible without involving direct loss or 

 destruction. After such a field for spotaneity had been 

 opened, consciousness would become a valuable and then 

 a necessary adjunct, and the effect of the reaction of con- 

 scious beings upon each other would be to widen the arena 

 for its display and increase the complexity of its activities. (') 

 Passing over the valuable evidence derived from human 

 pathology and so ably analyzed by Nothnagel and Naunyn('-) 

 and the digest of recent efforts in this direction given in 

 Brain during 1889 by C. K. Mills, we may examine, for 

 a moment the bearing of the most recent histological work. 

 A paper by Koelliker,( ') which appeared in December, 1890, 

 is occupied chiefly with the application of Golgi's method to 

 the study of the spinal cord. The positive anatomical 

 results may be summarized as follows: 



1. Sensory fibres on entering the cord divide into an 

 ascending and descending limb, which pass through the 

 dorsal column and lie on the surface of the substantia 

 gelatinosa. 



2. No connection of the dorsal root fibres with nerve cells 

 has so far been observed. 



3. The fibres of the longitudinal dorsal tracts give rise to 

 lateral branches (collaterals), which enter the gray sub- 

 stance, terminating in free stumps which are especially 

 abundant in the marginal zones of the substantia gelatinosa 

 and Clarke's columns. 



1 This subject was discussed in a lecture before the University of Cincinnati, April, 

 1891, a synopsis of which will be incorporated beyond. 



2 Verhand. des VI Congresses f. innere Medicin zu Wiesbaden, 1887. 



3 " Zur feineren Anatomie des centralen Nervensystems " Zeitschrift f. wiss. 

 Zoologie, Bd. LI, p. i. 



