238 PRACTICAL HISTOLOGY [XXXI 



In the 1st thoracic segment ; Goll's column is present, but runs 

 more to a point than in the upper cervical region, and is smaller ; 

 Clarke's nucleus is distinct, the neck of the posterior cornu is 

 rather long. (The anterior cornu has a considerable lateral 

 bulging in the upper part of this segment.) 



In the 1st or 2nd lumbar segment ; Clarke's nucleus is probably 

 present (it disappears in the lower part of the 2nd segment) ; 

 Goll's column is absent ; the oval area seen in the lumbar swelling 

 is represented by fibres near the surface in the 1st lumbar, rising 

 to the oval area in the 2nd lumbar ; the neck of the posterior 

 cornu is thick and the apex short. 



4. Section in sacral region (man). Note that the area of 

 this grey matter exceeds that of the white; the neck of the 

 posterior cornu is very thick ; the anterior cornu is large, its 

 outline rounded, it contains marked groups of large nerve-cells 

 with large nerve fibres between and amongst them ; scattered 

 large cells, forming the sacral nucleus, are present in the base 

 of the posterior cornu. 



5. Sections of cord of dog (3rd C. ; 7th C. ; 1st Th. ; lower 

 Th. ; 6th L. ; 2nd S.). Note the following differences from the 

 human cord : 



In the cervical region the cord is only slightly flattened in 

 outline, and the central canal is only slightly nearer the ventral 

 than the dorsal surface. The outer boundary of Goll's column 

 is concave. The neck of the posterior cornu is rather broad, and 

 its apex is fairly close to the surface. The fibres of the spinal 

 accessory 1st to 5th or 6th cervical segments are generally 

 more obvious than in man. The cervical swelling is more like 

 the lumbar swelling than it is in man. 



In the greater part of the region between the cervical and 

 lumbar swellings, Clarke's nuclei touch the posterior fissure, 

 thus giving an appearance of a very broad grey commissure 

 behind the central canal. In the two or three segments near 

 the swellings, they are less developed and farther from the p. f. ; 

 they cease about the 4th L. in dog, and 5th L. in cat. Goll's 



