425 



forming the brachium conjunctivum. In this stage the system has not 

 yet a fibrous structure, but consists of a reticular tissue, the meshes 

 of which are stretched in the direction of the ulterior fibres. The 

 meshwork stains deeply with eosine and is pretty nearly devoid of 

 nuclei; the sparse nuclei met with probably belong to glia- cells. This 

 reticular tissue, which everywhere originates in the intermediate layer, 

 constitutes bundles, all of which converge towards the mesencephalic 

 border of the cerebellum. It follows from this observation that it is 

 chiefly the intermediate layer that forms the rudiment of the central 

 nuclei of the cerebellum. 



The intermediate layer is covered by a cortex-layer (Fig. 1 C.) 

 which coats the external surface of the cerebellum (Herrick, Stroud, 

 ScHAPEK a. 0.). This 

 layer consists of cubic 

 epithelial cells, with a 

 large round nucleus 

 which deeply stains 

 with the haematoxyline 

 dye. It is entirely 

 distinct from the un- 

 derlying strata and 

 easily recognized by its 

 large nuclei. This layer 

 covers exclusively the 

 external surface of the 

 cerebellum and expands 

 upon the taenia (Fig. 

 6 0.) by which the 

 cerebellum goes over 

 into the tela chorioidea. 

 The thickness of this 

 layer is variable and 

 keeps in close con- 

 nection with the further form-differentiation of the cerebellar surface. 



As may be seen in Figures 1 and 2, the external surface shows 

 two shallow grooves which run parallel with each other and with the 

 posterior border of the cerebellum. The grooves are concave, with 

 their concavity turned to the anterior border; laterally (Fig. 2) the 

 grooves are deeper than in the middle region (Fig. 1). This ob- 

 servation is in accordance with the description of Stroud, who found 

 that the primary cerebellar grooves first appear upon the lateral region 



Fig. 4. Frontal section 4.7 mm distant from the 

 posterior border of tlie cerebellum. 15/1. C. cere- 

 bellum. Mes. mesencephalon. P. pons. S.b. sulcus 

 basilaris. T. taenia. T.ch.q. tela chorioidea of the 

 fourth ventricle. 



