8 ANATOMY OF THE CBNTEAL NEEYOUS SYSTEM. 



ever part of the brain he experimented he brought new and important things 

 to light. In addition to Gudden we are also indebted to Mayser, Ganser, 

 Forel, Monakow, and Lowenthal for important facts regarding the course of 

 fibers in the spinal cord, the method of origin of cranial nerves, the course 

 of the Tractus tecto-bulbaris in the brain, etc. 



Occasionally cases are observed when nature herself similarly performs 

 a Gudden experiment upon man. The author was able, in one case, to 



Cd4 



Eaf 



Cca 



B Tho FU 



Fig. 1. — Showing the fibres of the corpus eallosnm prepared by teasing with 

 forceps the hardened tissue. (After Henle.) 



follow far up the spinal cord atrophied nerve-tracts which had been arrested 

 in development through intra-uterine amputation of an arm; at another 

 time opportunity was offered to study the nervous system of a child which, 

 soon after birth, suffered an extended softening of the cortex of the 

 parietal lobes. In the spinal cord the crossed pyramidal tracts were com- 

 pletely lacking. 



The knowledge of the course of nerve-tracts has made notable progress 



