462 



THE INTERMEDIATE PRIMATES 



although in neither of these species does the tail differentiate as a prehensile 

 organ. In this light, the relative dimensions of the nucleus of GoII in the three 

 intermediate primates is significant in two of them, macacus and baboon, 

 because the inllux of discriminative impulses from the legs and tail is consider- 

 able. In the gibbon, wliich possesses no tail, sensory stimuh are correspondingly 

 reduced. The coeflicients of the nucleus of Goll in macacus, baboon and gib- 

 bon are shown in the appended tabulation: 



Coefficients of The Nucleus of Goll in the Intermediate Primates 



When the nucleus of Goll in the intermediate primates is compared with 

 the corresponding structure in the lower primates, equally striking con- 

 trasts become apparent. In mycetes, for example, this nucleus is the most 

 conspicuous. The preeminence of the nucleus of Goll in the howling monkey is 

 unquestionably related to the possession of a prehensile tail. Here again the 

 specialization in structure brings about new spheres of activity in the realm 

 of behavior. The nucleus of Goll in the gibbon has the smallest dimensions of 

 all the primates thus far considered. Its size is even less than that of the lemur 

 or marmoset. The specialization of the hindlimb, therefore, and the develop- 

 ment of the tail, as these factors bear upon the inilux of stimuli concerned in 

 discriminative sensibility and thus become active in the organization of the 

 animal's behavior, are clearly reflected in the primary receiving station for 

 these impulses in the brain stem, the nucleus of Goll. 



In the case of the nucleus of Burdach, however, the conditions are some- 

 what different. This nucleus in macacus is considerably larger than in either 

 baboon or gibbon. In all probabilitj- the difference is to be attributed to the 



