OF DENISON UNIVERSITY. 53 



The following measurements are added : 



Total length, 5 cm.; length of olfactory lobes, 12 mm.; from of 

 hemisphere to chiasm, 12 mm.; to posterior third nerve root, 24 mm.; 

 to bridge, 26 mm.; to posterior of pons, t,;^ mm Total width of cer- 

 ebrum at base, 32 mm; at chiasm, 26 mm.; distance between oppo- 

 site sulci rhinales at chiasm, 21 mm.; space between opposite pyriform 

 lobes at nearest point, 8 mm ; distance between fifth nerve roots, 10 

 mm.; distance between seventh nerve roots, 11 mm.; distance be- 

 tween sixth nerve roots, 5 mm,; distance between -eighth nerve roots, 

 12^ mm.; width of cerebellum at widest part, 25 mm.; width of cord 

 at base of medulla, 8 mm ; width of medulla near lower end, 13 mm.; 

 from anterior of bridge to first spinal nerve, 21 mm.; from anterior of 

 bridge to second spinal nerve. 25 mm.; from anterior of bridge to 

 third spinal nerve, 30 mm.; median length of hemisjjheres, 47 mm.; 

 width of cerebellum exclusive of vermiform, 22 mm. 



Structure of the cord and medulla. 



The cross sections of the cervical region of the cord of Antomys 

 show the relations of the white and gray matter to be rather primitive. 

 The minor subdivision of some of the longitudinal columns can not 

 be determined so readily as in higher types. 



The central gray matter divides the cord into the ventral, lateral, 

 and dorsal columns. Fig. i, Plate XIII, taken at the entrance of the 

 second cervical dorsal roots, shows the relations of these parts. 'I'he 

 ventral column is rather smaller in comparison to the lateral and dor- 

 sal columns. It receives fibres from the veiitral cornu, <7, and from 

 the anterior commissure, b. The lateral column is uniform in texture 

 and is not susceptible to a division into jjyramidal and ilirect cerebral 

 tracts by any markings on the sections. It receives a constant supj)ly 

 of fibres from the whole extent of the ventral column. The dorsal 

 columns show a decided difference in texture in different parts and can 

 be easily divided into the dorsal or Burdac h's columns, .c. dorsal me- 

 dian, or Goll's columns, //. 



In (toll's columns the transverse section shows but a small amount 

 of neuroglia and the section is entirely made uj) of nerve fibres, as 

 will be seen from Plate XIII, //>. 7, while Fig. 6 of the same j.Iate 

 shows the structure of Burdach's columns an I the lateral and ventral 



