SPECIAL CUTANEOUS SUBDIVISION. 135 



to the surface. The dendrites arise from the end of the cell next 

 to the molecular layer and spread in that layer. The dendrites are 

 noticeably straight, have a stiff appearance, and all their branches 

 in the molecular layer are provided with great numbers of little 

 spine-like projections. The possession of such dendrites brings 

 these cells into the same category with the Purkinje cells of the 

 human cerebellum. Since the dendrites are imbedded in the 

 myriads of fine fibers of the molecular layer it is probable that the 

 small spines serve for contact or perhaps a closer connection with 

 the fine fibers. A single Purkinje cell is shown in Fig. 39 and one 

 is drawn in the upper part of Fig. 67. From the inner end of the 

 cell-body, which is frequently slender and pointed, arises the 

 neurite which may take one of three courses. Some of them go 

 ventro-mesially close beneath the floor of the fourth ventricle 

 and either make connections with the motor nuclei of the cranial 

 nerves of the same region or enter the longitudinal fiber tracts 

 closely related to those nuclei and go to nuclei of more distant 

 nerves. The fibers from the cerebellum which have this desti- 

 nation form two or more bundles which curve down over the 

 inner face of the acusticum and reach the motor column in the 

 region of the trochlearis and abducens nuclei. All these fibers 

 may be referred to as the short motor connections of the acusticum 

 and cerebellum. Other fibers from the Purkinje cells, especially 

 in the acusticum, go as internal arcuate fibers to join the tractus 

 bulbo-tectalis. Still other fibers from Purkinje cells in the acusti- 

 cum go as arcuate fibers on the outer surface of the brain to desti- 

 nations which are as yet little understood. Some may go to a 

 nucleus comparable with the lower olive of human anatomy, 

 others go to the cerebellum. The latter would correspond to the 

 external arcuate fibers of man. The destination of the larger 

 part of the neurites of Perkinje cells in the cerebellum of lower 

 forms is not known. In mammals (p. 245) the neurites of Purkinje 

 cells are very widely distributed to distant parts of the brain 

 and spinal cord and it is an interesting problem to know how 

 low in the scale of vertebrates this condition makes its appearance. 

 The cells in the acusticum intermediate between these two types 

 are equally large but have not such definite form and arrange- 



