SIGNIFICANCE OF PHYLOGENETIC STUDIES 51 



then the dorsal olives develop and later on the principal 

 olive. In the Central Institute for Brainresearch Kooy 

 studied a great many series of sections of all classes of verte- 

 brates. From his studies it is plain, that the accessory 

 olives are relatively large in lower mammals, while the 

 principal olive gradually grows bigger in the ascending scale 

 in a oral-caudal direction. A comparison of Kooy's re- 

 sults and mine, obtained by the study of cases of neocere- 

 bellar atrophy, show that they agree in a large measure. 



At the present stage of science we do not know much 

 about the physiological significance of the inferior olives. 

 Experimental destruction of these formations has not given 

 clear results. Recent experiences in pathology of Mari- 

 nesco, Gans and others point to their having something to 

 do with motility. In a case, showing during life curious 

 involuntary contractions in several groups of muscles (myo- 

 clonic contractions) Dr. Gans and I saw an extensive atrophy 

 of the inferior olives, chiefly in the principal olive at both 

 sides. There were, however, also some small congenital 

 malformations in the cerebellum. Professor Precechtel of 

 Prague studied this brain in my laboratory and will shortly 

 publish the results. When taken in connection with other 

 observations it may be expected, that the system of the 

 inferior olives will play a role in diseases of the extra- 

 pyramidal systems. The physiological significance of the 

 neocerebellum certainly differs from that of the palaeo- 

 cerebellum. Hence we may be sure that the physiological 

 significance of the older part of the inferior olives differ 

 from that of the younger. 



From these observations you may get the impression, 

 that the combination of pathological anatomy and compara- 

 tive anatomy benefit both branches of science. 



Not unfrequently pathological processes prefer the 

 younger parts of the central nervous system as Edinger, H. 

 Vogt, Jelgersma and others hold. It cannot be expected 

 that the rule, that the younger parts of the nervous S3^stem 



