THE SIGNIFICANCE OF PHYLOGENETIC STUDIES 

 FOR THE NEUROLOGIST 



For nine years I had the privilege of studying pathological 

 anatomy of the nervous system at the Central Institute for 

 Brainresearch, Amsterdam, conducted by Dr. C. U. Ariens 

 Kappers. The phylogenetic development of the nervous 

 system, studied there, deeply impressed me. As chnician 

 and pathologist I worked out some subjects in this hne of 

 science. In my opinion an exact knowledge of the relations 

 in lower animals is valuable for the morphology, physiology 

 and pathology of the human nervous system. Ontogenetic 

 studies are of course no less important, but our knowledge 

 in this line is far from complete. 



To give you an impression of the significance of the 

 phylogenetic Hne of thought I desire to tell you something 

 about my research work in this matter. Yesterday, in 

 treating the pathology of sensibility, I gave some examples 

 relating to physiological anatomy. Today I shall discuss 

 morphology, pathological anatomy and clinical neurology. 

 I begin with the cerebellum. 



In the older literature the human cerebellum was divided 

 into a middle part, called the vermis with the flocculus and 

 two lateral parts known as the hemispheres. EUiot Smith, 

 Bradley and particularly Bolk divided the cerebellum 

 differently. In studying several classes of mamimals they 

 preferred a transverse division, while the former was sagittal. 

 The figure 9 shows the scheme of the cerebellum after Bolk. 

 There is an anterior part, called the lobus anterior and a 

 posterior part, called the lobus posterior. These are sepa- 

 rated from one another by a deep fissure, the sulcus pri- 

 marius. In the lobus anterior no division can be made into 

 middle and lateral parts. The lobus posterior is sub- 



45 



