SIGNIFICANCE OF PHYLOGENETIC STUDIES 49 



scheme of Edinger, figure 11 the results of the investigation 

 of my first case of neocerebellar atrophy. In figure 12 I 

 have drawn the results of the ontogenetic studies of van 

 Valkenburg. The latters results and mine, as you will 

 notice in the various figures, agree with those of Edinger. 

 In this way the older division of a vermis and two hemi- 

 spheres returned again. The sharp borders between the 

 atrophied parts and normal parts of the cerebellar cortex 

 in these cases of neocerebellar atrophy could not be fortui- 

 tous. The idea rose that these areas were changed, because 

 these belonged to the younger parts of the cerebellum. You 

 can thus understand that the conception of a palaeo- and a 

 neocerebellum appealed to me. 



Recently Marburg and Winkler advanced arguments 

 against this conception of Edinger. One of my pupils, 

 Dr. Koster, who studied two cases of neocerebellar hypo- 

 plasia in my laboratory, has given fuller data about the 

 different opinions in this matter. I refer you to his book. 



The brains of cases of neocerebellar atrophy I used to 

 increase our knowledge of other parts of the central nervous 

 system, connected with the cerebellum. I shall select as 

 an example the system of the inferior olives, an extensive 

 but mysterious formation in the medulla oblongata. 



The inferior olives consist of large groups of cells, which 

 send their fibres to the cortex cerebelli by the so-called 

 tractus olivo-cerebellaris, which chiefly proceeds to the 

 crossed side. These inferior olives degenerate when the 

 cortex of the cerebellum is destroyed. Now I found in two 

 cases of pure neocerebellar atrophy, that the degeneration 

 did not extend over the whole inferior olives. The system 

 of the inferior olives in man is composed of a principal olive, 

 very large here, and of two accessory ohves, a dorsal and a 

 medio-ventral one. In these above mentioned cases of 

 neocerebellar atrophy the accessory olives were spared, to- 

 gether with the oral part of the principal olive. The dis- 

 tribution of the degeneration is drawn in figure 13. 



