THE CEREBELLUM 609 



of cells : the granule cells, the large stellate cells and the so-called soli- 

 tary cells. The latter are small fusiform elements, but of their signifi- 

 cance and relationships little is definitely known. 



The GRANULE CELLS have a general distribution throughout the 

 granular layer. They are of relatively small size, multipolar, and pos- 

 sess short dendrons (frequently four) which end in claw-like processes. 

 These latter are in close relationship with the so-called eosin bodies, 

 small spheroidal finely granular masses having a special affinity for 

 eosin. The eosin bodies are believed by some to represent synapses 

 between the dendrites of the granular cells and the telodendria of the 

 centripetal mossy fibers contributed by the medulla. The axon of the 

 granule cell is unique among the cerebellar cortical neurons in that it 

 passes toward the surface; here it divides in T-fashion, the branches 

 passing parallel to the long axis of the convolutions thus coursing at 

 right angles to the dendronic expansion of the Purkinje cells, in relation 

 with which they probably end. 



The LARGE STELLATE CELLS have a limited distribution in the granu- 

 lar layer; they are more or less closely confined to the boundary zone 

 between the molecular and granular layers. They are large multipolar 

 cells, with a profuse dendronic contribution to the molecular layer, 

 and an almost equally profuse short axonic and collateral contribution 

 to the granular layer where the telodendria end in relation to the 

 granule cells. These are typical Golgi cells of the second type. 



THE MEDULLA 



The medulla next the cortex contain three important types of medul- 

 lated fibers : the climbing fibers, the mossy fibers, and the axons of the 

 Purkinje cells. The latter are centrifugal fibers passing to the internal 

 nuclei. The climbing fibers are so designated by reason of their end- 

 ing in profuse telodendria which are closely associated with the dendrons 

 of the Purkinje cells, apparently 'climbing' over them. The mossy fibers 

 owe their designation to the nodular mossy character of their terminal 

 branches within the granular layer. Their end-arborizations are in- 

 timately related to those of the dendrons of the granule cells prob- 

 ably contributing to the formation of the eosin bodies. 



Both cortex and medulla contain an abundant neurogliar supporting 

 substance. The astrocytes of the cortex are largely of the short-rayed 

 (mossy) type; those of the medulla are exclusively of the long-rayed 



