10 



LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



The third figure shows you a cross-section through the cer- 

 vical region of a spinal cord taken from a man who lost his left 

 arm before birth. You see that the gray and white substances, 

 particularly the former, are markedly atrophic on the left side. A 

 more careful examination of the extent of this atrophy gave a clue 

 to the location of the central termination of the divided nerves. 

 Our understanding of the general morphology of the cen- 

 tral nervous system has been advanced by nothing more than 

 by comparative anatomy and embryology. Questions of great 

 importance have been solved on the brains of fishes and am- 

 phibians. Leuret and Gratiolet, Meynert, Gottsche, Fritsch, 



Miclucho - Mac-lay, Rabl - Ilu'ck- 

 hard, Rohon, Wiedersheim, 

 Guldberg, Spitzka, and many 

 others have rendered service 

 in the field of comparative 

 anatomy. What we know of 

 the embryological development 

 of the organs we are now study- 

 ing we owe to Kolliker, His, 

 Tiedemann, Rcichert, von Mihal- 

 kovics, Gotte, Dursy, and Lowe. 

 The results of comparative anatomy have not been so great 

 as might have been expected so far as marking out the course 

 of nerve-fibres is concerned. 



Unlike the outer configuration of the brain, the finer struc- 

 ture has awakened little interest ; although the latter may be 

 said to be the kernel of the matter, while the former is but the 

 outside shell. It may be that this was largely due to the un- 

 satisfactory nature- of the methods of study available at the 

 time. Only a few among whom Stieda, Mayser, Fritsch, 

 Osborn, Bellonci, and Ahlborn may be mentioned here suc- 

 ceeded in distinguishing a few tracts and marking out a few 

 ganglia and the origin of a few nerves among the complicated 

 net-work of nerve-fibres which is present even in the lowest ver- 

 tebrate. For, simple and easily understood as the outer config- 



FIG. 3. 



Section through the cervical cord of a 

 man 45 year* old, \\\\:t suffered an intra- 

 uteriue amputation of the left forearm. 



