I 4 o PRACTICAL HISTOLOGY. 



white matter within and two layers of gray matter outside, 

 the inner of the two being the more intensely coloured, and 

 having a granular appearance with this magnifying power. 

 The cells of Purkinje may just be detected lying at the 

 inner part of the outer gray layer. 



(H.) Outer gray layer. The cells of Purkinje have a 

 single central process that passes into the inner gray layer. 

 It is often very difficult to see this, but there is no difficulty 

 in seeing one or two processes passing from the outer 

 aspect and dividing again and again, and thus forming a 

 network in the outer gray layer as the branching processes 

 of the cells of the spinal cord do in its gray matter. The 

 nuclei scattered here and there belong to the neuroglia. 



In the inner gray layer great numbers of nuclei are 

 easily seen. They closely resemble the nuclei of the neu- 

 roglia. 



2 48 A. Structure of Cerebrum. a. V. S. convolu- 

 tions of carminised human cerebrum. Mount in dammar. 



(L.) The convolutions are simple in character without 

 secondary folds as in the cerebellum. In very favourable 

 specimens a lamination of the gray matter may be seen. 

 This indeed in the unhardened brain is evident to the eye, 

 assisted by a simple lens. There are alternate white and 

 gray layers in the gray matter, but little heed need be 

 given to an examination of these with a low power, for one 

 of the layers that has a whitish appearance contains most 

 of the pyramidal cells that are so characteristic of the cere- 

 bral ganglion. 



(H.) It is really very difficult to succeed in getting a 

 specimen just thin enough, and just sufficiently well stained, 

 to show the five layers described in the gray matter by 

 Lockhart Clarke and Meynert. The student may very 

 possibly see little more than the pyramidal cells ; even these 

 will not be sufficiently seen if the section be not perfectly 

 vertical. The pyramidal cells occur about the middle of 

 the gray matter, of which they are the largest cells. Their 

 apices are directed outwards, numerous processes come off 

 from the base, and usually one from the apex. According 

 to Meynert, all the processes ramify excepting one the 



