LEMUR MONGOZ 43 



Another feature is the appearance of the caudal extremity of the 

 nucleus of Goil together \\'ith an extensive bundle t)f frbers which sur- 

 rounds it and forms the column of Goll (CO). This broad field of 

 myelinized axons makes a long ascent from the spinal cord, arising in those 

 levels which represent the dermatomes and proprioceptors of the tail and 

 lower extremity. In lemur, the nucleus of GoII and the surrounding fasciculus 

 have their special significance in the fact that the adjacent bundle of libers 

 m the column of Burdach is relatively more extensive. From this it may 

 be inferred that the parts of the body represented by the column of Burdach 

 possess more functional prominence than the parts represented by the more 

 mesial collection of fibers in Goll's column. This idea gains support from the 

 fact that the column of Burdach represents the upper extremity. In lemur 

 the manual differentiation of the forelimb is still far from complete. 

 Although all of the principal elements entering into the formation of the 

 hand are present, the upper extremity is in a distinctly low manual stage. 

 The disparity in size of these two columns speaks in favor of a less highly 

 developed functional adaptation in the use of the hindlimb and the tail than 

 in the forelimb and hand. 



Another feature in the dorsal region of the section is the marked expan- 

 sion of the substantia gelatinosa trigemini (nucleus of Rolando) (NR) 

 which serves as a relay station for all fibers bearing impulses from the 

 trige;TiinaI areas of the face and head.. This innervation includes regions 

 anterior to the interparietal line drawn across the vertex of the skull from one 

 external auditory meatus to the other. In an animal which has not yet 

 developed a hand to serve in capturing prey for food, the head, and partic- 

 ularly the mouth, affords an important organ of offense and defense. Such an 

 organ must be provided with an adequate sensory apparatus to guide it 

 in these essential efforts of life. Its sensory role in directing the course of 

 the animal as it makes its way through the leafy parts of the trees or through 



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