396 



THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



of the cortex of the subiculum, we come to the nuclear lamina, 

 which is thus the most external layer of cortical substance 

 contained in the fold of involution. 



1. This first cortical layer is indicated by m. The small 

 scattered cells of this layer are, for the most part, recognized 

 with difficulty, and are arranged parallel to the direction of 

 the fibres of the nuclear lamina. 



Fig. 237. 



Fig. 237. Scheme of the involuted layer of the cornu Ammonis with 

 the medulla of the alveus (Muldenblatt), and of the nuclear lamina. 

 m, The nuclear lamina with very small nerve corpuscles, which is 

 equivalent to the first lamina of the five-laminated portion of the cor- 

 tex ; I, territory of the stratum lacunosum, with a plexus formed by the 

 apical processes of the pyramids, equivalent to the second layer ; r, 

 the stratum radiatum, corresponding to the outer half of the third 

 layer; 0, the pyramids of the involuted lamina, equivalent to the 

 inner half of the third layer of the five-laminated cortex ; A, lamina 

 of the alveus, equivalent to the projection system of the medulla of 

 the convolutions that here, on account of the absence of the granule 

 and fusiform layer, attaches itself .immediately to C. 



2. The second layer, which contains none of the small pyra- 

 mids, forms a stratum lacunosum (Q (stratum reticulare of 

 Kupifer). The lacunae marked in fig. 236, 1, are formed by a close 

 plexus of perivascular spaces around a series of anastomosing 

 capillaries, by means of which the vessels of the nuclear lamina 

 supplied from the pia mater communicate with those of the 

 surface of the ventricle, which, proceeding from the ependyma, 



