216 JOURNAL OF COMPARATIVE NEUROLOGY. 
5. Summary of Determinations of the Area of the Entire 
Dermal Surface of the Human Body of Adult Men. 
Height Body wt. Area of 
imC€ms) ain) Ke: Dermal sur- 
Age face in mm?. Observer. 
17 years, well-built 169 55:5 1,920,550 MEEH (1879) 
20 years, 170 59-5 1,869,530 5G GC 
26 years, 162 62.3 1,895,960 66 oe 
36 years, corpulent 171 78.3 2,243,490 a ee 
36 years, emaciated 158 50.0 1,758,740 os ue 
45 years, 160 51.8 1,799,350 3 a 
66 years, 172 65.5 2,028,150 Ce uC 
(Not given) ? ? 1,584,300 KRAUSE (1844) 
(Not given) y ? 1,651,700 FUNKE (1858) 
(Not given) 162 50.0 1,606,685 FUBINI and BoONCHI (1881) 
Having now data for the number of cutaneous nerve 
fibers in the dorsal roots of the spinal nerves of man, and for 
the area of the dermal surface of the body, we are enabled to 
make calculations as to the innervation of the skin, not only 
for the body as a whole, but also for some of its principal parts. 
IV. THe INNERVATION OF THE DERMAL SURFACE OF THE 
Human Bopy. 
Z. Donaldson's Estimate. DoNALvson (1901) for the 
area of the dermal surface made use of the results obtained by 
Meen for a man weighing 136 lbs.—1,g00,000 mm’. For the 
number of cutaneous nerve fibers in the dorsal roots he took 
60% of STILL1NG’s estimate of 500,000, —300,000. According 
to this calculation, every cutaneous nerve fiber in the dorsal 
roots innervates, on the average, 6.3 mm” of the dermal 
surface. 
2. Vortschvillo’s Estimate. This investigator (1883) out- 
lined upon a cadaver the skin areas of the peripheral nerves as 
given by HENLE (1879). 
These outlines were traced on transparent paper, and the 
area of these outlines determined by placing this transparent 
paper upon a sheet of paper ruled in sq. cm. and sq. mm. 
According to his summary there are I19,337 cutaneous nerve 
fibers to innervate the 130,084 mm’. of dermal surface of the 
upper limb, or on the average one nerve fiber to every 
1.1 mm’. of skin; and 82,167 cutaneous nerve fibers (154,459 
