( 7) 



lobe of the cerebellum. Then the pecnliai* surface division in the 

 median line between sulcus primariiis (J) and lissnra secnnda (2) 

 deserves notice. The sulcus praepvramidalis (4), namely, at first 

 always divides this region into two nnequal parts ; the lower half, 

 the greater, situated between sulcus jiraepjramidalis (4) and fissura 

 secnnda is the origin of the pyramis, while from the very narrow 

 npper half, situated between sulcus primarius (1) and sulcns praepy- 

 ramidalis, mnst originate : declive, folium vermis and tnber vermis. 

 In this respect a parallelism can be noticed between the phylogenetie 

 and ontogenetic development of the cerebellum. F'or the narrow 

 region between sulcus primarius and sulcus praepyramidalis is 

 homologous with that lobulus which in the median section of the 

 mammalian cerebellum I have distinguished as lobulus C^ and which 

 only in the Primates attains a very strong development. 



The frontal plane and median section of the cerebellum of a foetus 

 of 15 cm. are given in fig. 10. This stage of development is important 

 because now the foetal human cerebellum shows the same lobulisation 

 which I Jearnt to be the fundamental type of the mammalian cere- 

 bellum generally, a stage which only lasts a short time, since now 

 soon the grooves appear that characterise the Primates generally or 

 the Anthropoids and man more particularly and tiie homologa of 

 which are missed with other mammals. For as will be seen from 

 fig. 10b, now in the median section, as well the lobus anterior as 

 the lobus posterior, is di\'ided by three groo\'es into four lobuli. 

 With the mammalian cerebellum I have distinguished the four lobuli 

 of the lobulus anterior as lobulus 1, 2, 3 and 4, the latter being 

 situated immediately before the sulcus primarius, the four lobuli of 

 the lobus posterior I distinguished as lobulus a (homologous with 

 the nodulus), lobulus h (homologous witli the uvula), lobulus C^ 

 (homologous with the pyramis) and lobulus C, (homologous with the 

 complex of declive, folium vermis and tuber vermis). It will be seen 

 by a comparison w\\\\ the investigations of Charnock Bradley, that 

 the stage with man, sketched in figs. 9 and 10, has a strong resem- 

 blance with a developmental stage which the cerebellum of other 

 mammals (pig and rabbit) traverse before the final lobulisation of the 

 cerebellum. However much the Primate cerebellum may in its final 

 form differ from that of other uiainmals the groundplan of its lobuli- 

 sation is, as is evident from the now sketched period of development, 

 not different from that of other mammals. In the next following stage, 

 however, it follows a development of its own, grooves occur, intro- 

 ductory to the lamellisation of the cortex, which are specific for the 

 Primates and which will be described in the second communication. 



