(510) 
Fig. 20. The 19th pair of roots *) 
sectioned on both sides. 
On both sides an insensible triangle is found, lying adjacent to the mid-ventral 
line (see flg. 20). The insensible area did not suffer any notable change during the 
next four weeks. Autopsy confirms the section of the 19th pair of roots. 
OBservATION IL. Young male dog. On December 27th 1901, under rigorously 
aseptic conditions, the 15th, 16th, 18th and 19th pair of roots to the right, the 
17th pair of roots to the left, are cut through extradural. The autopsy on Jan. 
13th 1902 confirms that the 17th root is intact to the right and sectioned to 
the left. The determination of sensibility on Dec. 28th shows the following : to 
the right, a sensible band between two insensible continuous bands ; to the left 
an insensible triangle lying adjacent to the mid-ventral line, including that part of 
the central area of the opposite dermatoma exceeding this line. 
Fig. 21. The 17th dermatoma. To the right, isolated between 
two sectioned roots, to the left cut through. 
To the right the caudal analgetic area is no longer a continuous band. Besides, 
it does not reach the mid-dorsal line because the sensible left half of the body, 
situated behind the caudal end of the section through the skin made at 27 Dec., 
exceeds there the mid-dorsal line. 
1) This figure has been obtained by counter-drawing the original photo on transparent 
paper in a few crude outlines, very carefully designing the boundary-lines, and 
afterwards reducing this figure, consisting only of a few simple lines, by photographic 
proceeding. The images, obtained in this manner, are highly demonstrative, if the 
analgetic areas are dotted, as has been done for all our figures. 
