TeLEXCEPHALOX NOX-OLFACTORV PORTIOXS 107 



previously noted (p. 96), while the rest is somatic in its 

 relations, like the remainder of the corpus striatum. 



The globus pallidus is a much smaller mass than the 

 neostriatum.^ It lies directly medial to the putamen, from 

 which it is distinguished by the fact that it contains a large 

 number of diffuse myelinated fibres. In man and many 

 other animals, it is divided up by thin lamellae of such fibres. 



The caudate nucleus and the putamen receive axons 

 through the internal capsule from the thalamus — particularly, 

 probably, from the centre of Luys and the anterior nucleus — 

 while some also come from the red nucleus. Perhaps col- 

 laterals from descending cortical fibres also end here. Associa- 

 tion fibres connect the striatal nuclei, but are stated to run 

 chiefly from the caudate nucleus to the putamen and from 

 this to the globus pallidus. There are probably descending 

 fibres accompanying the afi^erent ones mentioned, but most 

 of the descending fibres, at least in higher mammals, seem 

 to come from the globus pallidus through the ansa lenticularis, 

 whence they are distributed to the hypothalamus, the sub- 

 thalamic body, the substantia nigra, and the red nucleus. 

 There is, further, an extensive, difi^use fibre-connection between 

 the lentiform nucleus and the overlying pyriform cortex. 



The functions of the corpus striatum are as yet very 

 uncertain. It seems to have an influence upon muscle tone 

 and also to act upon the visceral nervous system. 



Related to the parts which we have been considering, is 

 the amygdala (archistriatum of Kappers and his school), 

 which difl^ers from them in receiving several orders of olfactory 

 fibres. Its function, however, is by no means entirely 

 olfactory, as is shown by its considerable development in 

 the dolphin, a totally anosmatic mammal. The amygdaloid 

 complex is to be regarded as a correlation mechanism for 



^A closely related group of cells, the basal or central nucleus or nucleus 

 ansae pediincularis , is apparently incorporated in the globus pallidus itself 

 in the rat. 



