42 



Lewis and Clarke on the Cortical Lamination [Jan. 24, 



the large multipolar cells in the anterior column of the cord. It will 

 naturally be asked how Meynert could have overlooked this important 

 layer of cells. Our explanation is, that whilst failing to regard them 

 as a layer distinct from the third, yet the existence of these individual 

 elements was recognised by him, as he states that the cells of the third 

 layer progressively augment till they attain the length of 40/x. # As 

 the largest cells of the third layer, however, but rarely attain such 

 dimensions, we presume that he had in view the elements to which we 

 now allude, probably regarding the depth at which they were placed as 

 an exceptional condition. Baillarger, on the other hand, whilst recog- 

 nising the layer, has also, we think, fallen into the error of misplacing 

 it in the order of cortical lamination. The error consists essentially in 

 placing these cells on too low a level, in fact, between the angular and 

 spindle cells, whilst the many hundred specimens examined by us 

 enable us to localise this series midway down the band of angular ele- 

 ments, a position maintained with singular uniformity. Dr. Majorf 

 follows Baillarger in regarding the cortex of the vault and that of the 

 central lobe as consisting of six layers. Mierzejewski^ and Betz || follow 

 Meynert, and refer to a five-laminated type, but the large cells of the 

 cortex more particularly have been made the subject of special study 

 by both writers. The position of these great cells being such as we have 

 described, one of two schemes must be accepted as representing the 

 normal lamination of this region. Either the layer of angular cells 

 above these great elements must be regarded as a series separate from 

 those below the same, thus making the type common to this region of 

 the cortex consist of seven laminae, of which the great cells referred to 

 constitute the fifth ; or, on the other hand, these latter cells with the 

 belt of angular elements above and below may be regarded as a single 

 layer, and termed the mixed or ganglionic series. We incline to the 

 latter as the preferable arrangement, for, apart from the consideration 

 that the former plan introduces an unnecessary multiplication of the 

 series of layers, there remains the important fact that the series of 

 large cells alluded to is not a constant layer. Indeed, there are exten- 

 sive portions even of the ascending frontal gyrus when these elements 

 are wholly absent. 



At these sites the angular elements present the appearance of a single 

 undivided belt. We are thus compelled to regard this remarkable 

 layer of cells as an intercalated series, and regard it as preferable still 

 to adhere to Meynert's five-laminated type, assuming the fourth layer 

 (which we term the ganglionic layer) to be subject to the modification 

 above alluded to. Far more importaat considerations, however, than 



* Op. cit., p. 386. 



f " Histology of the Island of Reil." West Riding Asylum Med. Reports, vol. "vi. 

 X "Etudes sur les Lesions Cerebrales dans la Paralysee Grenerale." Archives de 

 Physiol., 1875. 



|| " Grehirncentra." Betz, Centralblatt f. d. Med. Wissensch., Aug., 1874. 



