114 BRAINS OF RATS AND MEN 



out directly into the medial forebrain bundle. This 

 region probably serves for the correlation of olfactory 

 with tactual and other exteroceptive stimuli and may 

 be concerned chiefly with locomotor and facial re- 

 flexes involved in feeding. 



The first and second components of the striatum 

 complex are much more extensive in lower mammals 

 than in higher. Between and above them is a third 

 component which is also very ancient. 



3. The nucleus lentiformis, or somatic striatum, 

 receives no olfactory fibers, but large tracts which 

 ascend from the exteroceptive and proprioceptive 

 centers of the thalamus. It consists of a receptive 

 part (primitive putamen) and an emissive part 

 (globus pallidus) of large cells whose axons descend 

 by way of the internal capsule (lateral forebrain 

 bundle) to the motor centers of the cerebral peduncle. 



4. To these ancient parts there is added in reptiles, 

 birds, and mammals a new striatum which is incorpo- 

 rated into the older caudate and lentiform nuclei — 

 the hypopallium of the preceding description. This 

 is related physiologically with pallial territory and 

 has very different significance from other parts of the 

 striatum complex. 



This new striatum is an anatomically distinct 

 structure in adult reptiles and mammalian embryos. 

 It is the hypopallium of reptiles, in the restricted 

 sense in which I use the term, the "nucleus caudatus" 

 of Johnston's account (1923) of reptiles and embry- 



