1905.] 



Cord of the Macaque Monkey. 



91 



between the dorsal and the ventral portions of the grey substance, an 

 arbitrary division was made as follows : In each half of the cord a line was 

 drawn from the middle of the central canal to that point where the white 

 substance projects furthest into the grey substance (see fig. 1). The grey 

 substance dorsal to this was designated " dorsal horns," and that ventral to 

 it the " ventral horns." From the seventh lumbar region (middle portion) 

 downwards, a modification of this method was rendered necessary by the 

 presence of the fibres of the formatio reticularis. The lines were therefore 

 drawn from the central canal, in the manner already described, to the 

 corresponding points which were still discernible, and then continued in a 

 horizontal direction through the fibres of the formatio reticularis (see fig. 2). 



The " ventral horns " were measured in each case and the section area of 

 the " dorsal horns " determined by subtracting the figures obtained for the 

 "ventral horns" from the sum of the total grey substance. The "dorsal 

 horns " therefore include Lissauer's " marginal zone," the substantia spongiosa 

 and the substantia gelatinosa Kolandi. 



Owing to the lack of sufficient differentiation, it was not possible to make an 

 additional measurement of the substantia gelatinosa Eolandi. In a " control " 

 monkey, fixed with picro-corrosive formaldehyde solution containing 20 c.c. 

 instead of 10 c.c. formol for 100 c.c. of picro-corrosive solution, it appears to 

 be possible to do this, but the work has not been carried out as yet. 



Each table of figures is accompanied by a chart with curves, representing 

 the same graphically. 



In drawing the curves the same type of line and the same lettering have, 

 as far as possible, been used throughout the series to denote the same 

 constituent of the cord. The curves are to be read from left to right. -•• 



Fig. 1. 



Fig. 2. 



