348 Journal of Couiparathe Neurology and Psychology. 



the white matter adjacent to the gray appears darker than at 

 the periphery of the section. That this darkening is not due 

 wholly to mere enlargement of fibers already medullated at 

 thirty days is inferred from the presence of small fibers in all 

 parts of the cord. 



In order to determine in how far new medullated fibers 

 were responsible for these appearances a tentative enumeration 

 of the fibers in several areas of the cervical cord was made. 

 The areas chosen are represented diagrammatically in text-figure 

 1 1 below. 



Diagram of the cervical cord indicating the areas in which an enumeration 

 of fibers was made. 



In comparing the enumeration of these fibers in the adult 

 with an enumeration in similar regions of the young at birth 

 we find that in the adult there has been both a slight increase 

 in the number of fibers and a considerable increase in their aver- 

 age diameter. The following table presents evidence of increase 

 in number of fibers in the given areas between birth and ma- 

 turity. The standard area within which the fibers were counted 

 contained .00366 sq. mm., i. e., it was .06048 mm. on a side. 



Table Showing Number of Fibers in Given Areas of the Cervi- 

 cal Cord at Birth and at Maturity. 



Dorsal funiculus. Lateral fun. Ventral fun. 



At birth, 301 ''S-S^ 21S '^ 



Adult, 408 203 '' 246 -' 



* Average of enumeration at periphery and at margin of ventral column. 



[56] 



