(89) 



the Uvula and Tonsillae. Like the Pyiamis tlie Uvula too very soon 

 shows one or two transversal grooves, whicli do not penetrate into 

 the Tonsillae. The surface of the last called loliules remains unfolded 

 for a remarkably long time (Fig. 17 from a foetus of 29 cM. and 

 fig. 18 from one of 32 c.M.) and assumes an oval-shaped rounding. 

 But, the folding of the cortex once commenced, it proceeds in the 

 same way as in the under part of the lobulus biventer. For as can 

 be observed in Fig. IQ and 19, the grooves begin on the margin of 

 the lobules, i.e. laterally and grow out mesially. In connection with 

 this last fact it must be recalled to mind that also the fissure which 

 separates the Flocculus from the remainder of the cerebellum first 

 appears at the lateral edge of the latter and lengthens afterwards in 

 a mesial direction. 



The Flocculi and Nodulus have undergone but little differentiation 

 during the described stages of development; the Nodulus has increased 

 in surface and in the number of its grooves; while the Flocculus 

 in an foetus of 35 c.M. (Fig. 19c) shows only three lamellae. 



A distinct differentiation between the cerebellum and pedunculi 

 pontis is indicated sharply in foetus of 25 to 30 c.M. (Cf. 15c, IQh, 

 11a and 19c). In the foetus of 29 c.M. (Fig. 11a) the fossa lateralis 

 is sharply bordered while the sulcus superior posterior (x) ends in 

 its fore border and the sulcus horizontalis in its top. 



In the development of the human cerebellum some interesting 

 phenomena may be observed, which are worth to be brought in the 

 fore-ground and which may be summarised in the following way. 



1^"^ . In the grooving of the human cerebellum two stages may be 

 observed ; in the first stage those grooves arise that in general are 

 characteristic for the mammalian cerebellum. By these primary 

 grooves the organ is divided into an anterior lobus, which is sub- 

 divided into four lobules, and into a posterior lobus, which in the 

 median plane is also subdivided into four lobules. All these groo\'es 

 take their origin in the middleline. Besides these another groove 

 appears, beginning at the lateral border of the cerebellum (Fissura 

 parafloccularis). In the second stage those grooves become A'isible, 

 that are typical for the cerebellum of the Primates. 



2'"^^. After the primary grooves in the first stage having been formed 

 the further lobulisation and lamellisation takes place in the second 

 stage in a regular way. In the anterior lobe all the grooves take 

 origin in the middleline and lengthen laterally ; the same happens 

 with the maingrooves of the region between sulcus primarins and 

 bipartiens, but in the last region there also arise grooves in the 



