12 



The Structure of the Spinal Cord of the Ostrich 



further advantage that here the boundary of the dorsal funiculi is more 

 sharply defined, owing to the larger number of entering dorsal root-fibres. 



The results of the method in our case are represented in the adjoin- 

 ing table : 



TABLE 



SHOWING SIZE OF VARIOUS AREAS OF CROSS-SECTIONS OF CORD AT DIFFERENT LEVELS. 

 THE NUMBERS GIVEN INDICATE SQUARE MMS. 



These areas and their relative size are more graphically represented in 

 the diagram given in Fig. 4. The size of the grey substance, the ventro- 

 lateral funiculi, and the dorsal funiculi in typical segments are repre- 

 sented by curves, the height of which signifies square mms. as shown 

 by a scale on the left. 



From this diagram it is apparent that the ventro-lateral funiculi form 

 by far the greatest area at all levels. The proportion is much greater 

 cibove than below the lumbo-sacral enlargement. This could be ac- 

 counted for in part by the presence of tracts connecting the enlargement 

 with the brain centers. In both the cervical and lumbo-sacral enlarge- 

 ments the increase in area of the ventro-lateral funiculi is greater than 

 that of the grey matter and dorsal funiculi. This is doubtless due to 

 the large number of association fibres which form a field of fine fibres 

 surrounding the anterior horns. 



