1^6 . Journal of Comparative Neurology. 



alis) to be 32 mm. The maximum diminsions are claimed for 

 the IVth cervical segment. Thence the diameters decrease on 

 approaching the pars thoracaHs until thoracic V is reached. 

 This segment, not given in the table, had a lateral diameter of 

 21 mm. and a dorso-ventral diameter of 15.5. F'rom this seg- 

 ment to thoracic XII (also not given) the diameters remained 

 about the same, the lateral varying from 20 to 21 mm., while 

 the dorso-ventral maintained 15.5 to 16 mm. even as far as 

 thoracic XVII. In thoracic XIV, however, the lateral diame- 

 ter began to increase and in thoracic XIX and lumbar I attained 

 its maximum for the intumescentia lumbalis ; i. e., a lateral di- 

 ameter of 26 mm. with a dorso-ventral of 17 mm. Thence be- 

 gan the decrease toward the conus meduUaris. 



The segment of the author's specimen possessing the max- 

 imum dimensions was the Vlth rather than the IVth cervical. 

 It may be further noted that the lateral diameter of the Ilnd 

 thoracic segment of the author's specimen is greater than 

 that of the corresponding . segment of Kopsch's specimen. 

 The author's specimen may have been more swollen by the 

 action of the formalin in which it was preserved than had it 

 been preserved in Muller's fluid, but this would not explain 

 the difference shown in the table. There must be some mis- 

 take in the statement by Kopsch that the intumescentia cervi- 

 caHs reaches its maximum in the IVth cervical segment. Al- 

 though the author's specimen had been divided into several 

 pieces which had to be fitted together in sequence to determine 

 the numbers of the consecutive segments involved, this could 

 be accomplished with no great difficulty and the author is quite 

 positive that the largest segment of the intumescentia cervicalis 

 of his specimen was the Vlth and not the IVth. Further- 

 more, of the eleven other mammals dealt with in the compara- 

 tive studies to be mentioned later, the most enlarged segment of 

 the cervical region was usually the Vlth. The largest segment 

 is sometimes the Vllth but is never more cephalad than the 

 Vth. It is possible that Kopsch, by chance in this one instance, 

 failed to take into account the two segments of his specimen 



