154 JouKNAi. OF Comparative Neurology, 



segments is to be expected from the greater size of radices 

 posteriores of the more cephalad thoracic segments. All of the 

 afferent axones, so disposed, do not set-m to enter the confines of 

 the nucleus directly. Many of them seem first to collect in minute 

 fasciculi on the dorsal side of the nucleus [D, Fig. i6). These 

 minute fasciculi disappear in the more caudal sections and it is 

 assumed that they are axones passing caudad to enter the nucleus 

 at other levels. No doubt many of the axones observed as cours- 

 ing longitudinally in the nucleus are of this type. 



In a recent description of the medulla spinalis of the 

 orang-outang {Satyrus niger) Figueireuo-Rodrigues ('oi) noted 

 many medullated axones coursing in the nucleus dorsalis. In 

 his figures these appear more numerous than is usually de- 

 scribed for man. He describes them as varying in amount at 

 different levels and considers them as derived from the radix 

 posterior. He describes but one section from the thoracic 

 region and does not state from what segment this is taken. He 

 goes into little detail in dealing with this part of his specimen 

 and, with reference to the axones from the nucleus dorsalis, simply 

 makes the general statement (p. 441) that these pass out in the 

 direction of the fasciculus cerebello-spinalis. This author fur- 

 ther shows that the nucleus dorsalis of the orang-outang ac- 

 quires its greatest number of cell bodies and contains the great- 

 est number of transversely cut axones in the Ilird lumbar seg- 

 ment. This is interesting because, in man. the nucleus is 

 usually described as extending only between this segment and 

 the Vllth cervical, and therefore its caudal termination usually 

 occurs in the Ilnd lumbar. His figures, however, show that in 

 the orang-outang the most enlarged portion of the intumes- 

 centia lumbalis occurs in the Vlth lumbar segment, instead of 

 in the 1st or Ilnd as is usually the case in man. For the ele- 

 phant, KoPSCH describes the most enlarged portion of the 

 intumesCentia lumbalis as occuring in the caudal end of the 

 XlXth thoracic segment. 



FiGUEiREDO RoDRiGUES describes the axones coursing in 

 the nucleus dorsalis of the orang-outang as being collected 

 around the periphery of the nucleus, appearing in transverse 



