SIGNIFICANCE OF PHYLOGENETIC STUDIES 53 



A good example of this is the brain of a man, who con- 

 tracted in his third year an encephahtis, causing a leftside 

 hemiplegia and an epilepsia. This man died at the age of 49. 

 At the post-mortem examination the right side of the telen- 

 cephalon was much smaller than the left and there was 

 microgyria of the cortex. Studying this brain in a complete 

 series I found that the forebrain was largely destroyed, but 

 that the boundaries of this lesion were not fortuitous. 



The brain could be divided into three parts. In the first 

 the alteration was very intensive, in the second less so, 

 while in the third it was normal. The different areas may 

 be seen in figure 14. The frontal area was very intensively 

 damaged, while the sensu-motoric area in contrast showed 

 much less changes. The ventral part of the parietal lobus, 

 called the regio supramarginahs and angularis, was also 

 very intensively changed. 



In the occipital lobe a difference was very clear. The 

 primary optic field in the cortex was spared, the lateral 

 surface of the occipital lobe however (field 18 and 19 of 

 Brodmann) showed alterations. A comparison of these 

 drawings with the figure 15, in which a sketch is made of the 

 development of the various areas in the ascending scale 

 after the investigations of Brodmann, shows that the 

 phylogenetically younger parts of the cortex are in my case 

 intensively changed. It is often thought, that such ex- 

 tensive areas of destruction correspond with territories, 

 which are supplied by blood-vessels, but in my experience 

 this is frequently not so. 



It cannot be fortuitous, that the frontal brain, the part 

 of the pallium, that undergoes the greatest changes in the 

 phylogenetic development suffers so frequently from various 

 pathological processes. When, in the case here described, 

 we at present pass by the most ventral part, the lesion 

 stopped just at the sensu-motoric field, the area frontalis 

 being intensively damaged. Descending in the scale of 

 mammals this area frontalis gradually gets smaller. 



