134 



b, AssocLatLoe ani Commlnsaral 1 eurones. -- A second type 

 of neurone founi in the pallial eminence is distinguished from 

 the preceding one by its associative or cotniiissaral value, and 

 it is also readily recognizable by its soialLer size (Fig. 40). 

 The cell-body tends to retain a globular form. It gives ori- 

 gin to tfo or three dendrites which radiate frorn it at equidis- 

 tant points. The dendrites are only moderately stout, and 

 they are never of great length. They branch but a few times. 

 Their surface is sparsely studded with small gemmules. The 

 axone nay terminate on the same side of the brain; or it may 

 enter the pallial commissure, (Fig.31,p.c. ), for decussation, 

 terminating in the opposite half. The neurone shown in F'ig. 

 40 is an example of the commissural class. 



The internal structure of a neurone of either the associa- 

 tive or the commissural type is drawn in Fig. 63, as.n. The 

 nucleus is a subspherical mass, so large that it occupies prac- 

 tically the whole of the cell-body. The only cytoplasm dis- 

 tinguishable is that which composes the bases of the dendrites. 

 The nucleus stains quite deeply, owing to the dense reticulum 

 of chromatin which pervades it. The cytoplasm has only a few 

 tigroids of small size, an evidence of a feeble degree of activ- 

 ity for this type of neurone. 



a. Cajal Veuroiea. — Still a third type of neurone is 

 clearly the representative of the Cajal cell which Ramon y 

 Cajal ('91) described from the cerebral cortex of the rabbit. 



