Chapter XIV 



ORIGIN, COURSE, AND TERMINATION OF THE VISUAL 



RADIATION. LOCATION AND EXTENT OF THE VISUAL 



PROJECTION CORTEX. PROJECTION OF THE 



LATERAL GENICULATE BODY UPON THE 



STRIATE AREA (FINDINGS) 



In five of the experiments reported here (Experiments I, II, III, 

 IV, and V-a) the visual radiation was partly interrupted. The inter- 

 ruption was made either at the origin of the visual fibers in the external 

 geniculate body or close to it. In each of these experiments the inter- 

 rupted portion of the radiation degenerated toward the occipital lobe 

 and was traced in successive sections of the continuous five series, 

 stained according to Marchi 's method, to its respective cortical termi- 

 nation. The purpose of such a study was not only to determine the 

 general course and termination of the visual radiation but also to 

 analyze its constituent bundles — their mutual or relative position, 

 their course, and especially the relation of each of these bundles to its 

 special origin in the external geniculate body on the one hand, and to 

 its special segment of the visual cortex on the other. Since the seat of 

 the injury in each of the five experiments was somewhat different, the 

 bundles degenerated in each case were only partly identical. By 

 comparing all bundles or segments degenerated in all five experiments 

 one with another and by checking up the results of the present investi- 

 gations with those obtained previously by Brouwer and Zeeman, an 

 attempt has been made to reach a properly supported conclusion as to 

 the organization and function of the entire afferent visual path. 



In addition to this five other experiments are reported here where 

 either small portions of the striate area (alone or with a portion of 

 the visual- radiation) were damaged (Experiment V-b and V-c) ; or 

 where the striate area was almost or entirely removed (Experiment 

 V-D and V-e). In these experiments the purpose was to study the 

 retrograde cell degeneration of the lateral geniculate body according 

 to Nissl's method and in particular (a) to correlate the number, the 

 size, and the position of small degenerated zones in the lateral geni- 

 culate body with the number, the size, and the position of the lesions 



