INGBERT, Cutaneous Innervation in Man. 221 
distributed to muscles and deep tissues. The afferent fibers of 
spinal ganglion origin passing in the vam communicantcs are not 
separately considered in this estimate, but for the moment are 
classed with those passing to the skin. 
2. According to my estimate (using the skin areas fora 
large man), one cutaneous nerve fiber in the dorsal spinal roots 
innervates, on the average, 1.08 mm’. of the skin of the head 
and neck, 1.30 mm’. of the skin of the arm, 2.05 mm” of 
the skin of the entire body, 2.45 mm”. of the skin of the leg, 
and 3.15 mm. of the skin of the trunk; and for each addi- 
tional class of nerve fibers assumed we must increase the area 
proportionately. 
3. If we assume, with Fosrer, four classes of cutaneous 
nerve fibers, then each fiber will have to innervate, on the 
average, 4.32 mm’. of the dermal surface of the head and neck, 
and 12.6 mm’. of the dermal surface of the trunk. 
4. If there be four classes of afferent nerve fibers in the 
dorsal roots of the spinal nerves of man, then a histological 
examination of the nerve terminations in the skin ought to 
show each cutaneous nerve fiber to innervate, on the average, 
areas of skin as large as given above. 
VII. BIBLIOGRAPHY. 
Donaldson, H. H. 
1901. Am. Text-Book of Physiol.. Phzladelphia, and London, Vol. Il, 
p. 230, 
Foster, M. 
1891. Physiology, Pt. 1V, London, ps 281. 
Fubini, S. and Ronchi, J. 
1881. Untersuch. z. Naturl. d. Mensch, u. d. Thiere. XII, p, 26. 
Funke, O. F. 
1858. Untersuch. z. Naturl. d. Mensch, u. d. Thiere, IV, p. 36. 
Henle, J. 
1879. Handb. der Systemat. Anatomie. Braunschweig. Bd. \II, Abthe 
I, pp. 554 and 594. 
Ingbert, C. E. 
1903. Journ, Comp. Neur., Granville, Vol. XIII, p. 53. 
