A BY, Blood Capillaries in Cerebellar Cortex. 33 



exceeds those in the molecular layer. As to arrangement, it 

 may be stated in general that the vessels of the molecular layer 

 stand at right angles to the pia mater, while the vessels of the 

 granule layer lie in planes parallel to the pia mater. The mesh 

 in the molecular layer is of the elongated type, while that in 

 the granule layer is not elongated. 



It may be stated in general that the mesh in the granule 

 layer is closer than in the molecular layer, this following as a 

 corollary to the proposition regarding the relative number of 

 capillaries, provided the calibers are approximately equal. 



From what I have previously stated regarding the layer of 

 Purkinje's cells, it is clear there is not much possibility of insti- 

 tuting a comparison between that layer and the others, regard- 

 ing the question of vascularity. 



Considering the cortex as a whole, it may be regarded as a 

 distinct vascular organ, sharply defined from the medullary 

 layer. It is a remarkable fact that the capillaries of the granule 

 layer, at the boundary zone between the granule layer and the 

 medullary layer, turn upon themselves and form loops which 

 very strongly remind one of the arrangement of capillaries at 

 the inner surface of the gastric mucosa ! In the plate, 3 and 5 

 point to situations showing this peculiarity. The plate shows 

 in all parts how clearly defined the cortex is from the medullary 

 portion. 



It remains to call attention to certain regions where sepa- 

 ration of the granule layer from the molecular layer has oc- 

 curred. At 8 and 1 2 may be seen elongated clearer spaces, 

 the line 1 1 also traverses such a space. These are probably to 

 be regarded as artificial, but they serve to point out that the 

 granule layer and molecular layer of the cortex are really two 

 organs, considered as to vascularity. 



