SIGNIFICANCE OF PHYLOGENETIC STUDIES 55 



I shall now refer to the occipital lobe. As before de- 

 scribed, the regio calcarina was better spared than the other 

 parts of the occipital lobe. Now we see in figure 15 that 

 the regio calcarina or area striata in the descending scale of 

 mammals gradually predominates over the other optic 

 fields. It is already clear in monkeys and in rabbits almost 

 the whole optic field is occupied by the area striata, while 

 in the hedge-hog nothing else is found than this primary 

 optic field. 



The regio hippocampi with the cornu ammonis were 

 practically normal in our sections. They belong to the 

 older parts of the cortex cerebri. Descending in the scale 

 of mammals these parts gradually dominate over the other 

 fields. It may be seen, that this so-called archipallium in 

 the rabbit is much larger and that in the hedge-hog it is 

 even the biggest field of the cortex. The same holds true 

 in the regio retrosplenialis and in the frontal portion of the 

 temporal lobe (the uncus) which are older in development 

 and in my case are practically normal. 



As I described above the lesion in the frontal area stopped 

 just at the sensu-motoric field. This is not true, however, 

 regarding the most ventral part of this latter area, as you 

 may see in my figure 14. We know from recent investiga- 

 tions that it is just this part of the sensu-motoric area that 

 is developing later. 



Ontogenetic and phylogenetic development run along 

 parallel lines. In this respect it is interesting to notice that 

 Gans found in several cases of atrophy of the cortex in older 

 men, that the parts of the pallium, that had been latest in 

 myelinisation, suffered most. This is in keeping with the 

 above reasoning. 



We shall now follow the same line of thought in a clinical 

 subject. In a slightly different way Hughlings Jackson 

 did this already in the case of more general clinical problems 

 and in later time he was followed in this by Head, Mott, v. 

 Monakow and others. 



