1 14 "Journal of Comparative Neurology and Psychology. 



TABLE IV. 



Rate of MeduUalion in the Second Cervical Nerve oj the White Rat (Ransov). 



Medullated Fibers in the Medullated Fibers in the 

 Age. Dorsal Root. Ventral Root. 



1 2 days 1 608 



12 days 1 52 1 



12 days (average) 1564.5 



72 days 2472 689 



72 days 2394 660 



72 days 1059 590 



72 days 2217 591 



72 days (average) 2261 632 . 5 



6 months 2891 773 



6 months 2689 703 



6 months (average) 2790 736-5 



THE NERVE. 



1. The proportion of sensory and motor fibers. — All investi- 

 gators have found a larger number of fibers in the dorsal than in 

 the ventral root. According to Ingbert ('04) the ratio of all the 

 motor and sensory fibers arising from the left side of the human 

 spinal cord is i : 3.2, and from the second cervical segment alone 

 I : 6, Hatai ('03) working with the C. VI, T. IV, and L. II 

 nerves of the white .rat finds an average ratio of i : 2.3. The 

 normal relations in the C. II nerve of the white rat are expressed 

 in the following table, representing the writer's enumeration of the 

 ventral and dorsal root fibers for that nerve. 



T.\BLE V. 



Number oj Ventral and Dorsal Root Fibers in the II C. Nerve of the White Rat (Ranson). 



Age. Ventral Root. Dorsal Root. Ratio. 



72 days (no grms.) 689 2,472 1:3.6 



72 days (no grms.) 660 2,394 i'3-6 



72 days (no grms.) 590 ^,959 ' • 3-3 



72 days (no grms.) 591 2,217 1^3-7 



This table shows that the ventral root fibers are about 28 per 

 cent as numerous as the dorsal root fibers. 



2. The distal excess. — As has been said, considerably more 

 sensory than motor fibers enter into the formation of the peripheral 

 nerve. But, when we compare the sum of the fibers in the ventral 

 and dorsal roots with the total number present on the distal side 

 of the ganglion, we find a distinct excess on the distal side. The 

 earlier investigators who undertook to compare the number of 

 fibers on the two sides of the ganglion, either found them equal or 



