INGBERT, Dorsal Roots of Spinal Nerves, 73 
VI. The Classes of Nerve Fibers in the Dorsal Roots of the 
Spinal Nerves of Man. 
That the dorsal roots of mammals are pathways for affer- 
ent nerve impulses has been considered as demonstrated since 
the time of Bett (1811)”. This fact has been so often con- 
firmed in man as the result of injury and disease as to need no 
further discussion. But whether the dorsal roots of man con- 
tain efferent nerve fibers in addition to the afferent, is yet an 
open question. The histological studies of v. LENHOSSEK 
(1890)*, Caja (1890) and (1893)”, VAN GEHUCHTEN (1893)”, 
ReEtzius (1892)”, and Martin (1895)”, have demonstrated in 
the chick the existence of neurones, the cell bodies of which 
are located in the spinal cord and the axones of which pass out 
of the cord by the dorsal roots. It is inferred that these neu- 
rones are efferent, but the demonstration of this is still lacking. 
By physiological experiments STEINACH (1893 and 1898)”, 
STEINACH and WIENER (1895) and Horton Situ (1897)" 
have demonstrated the presence of efferent fibers in the dorsal 
roots of the frog. 
The degeneration method has given contradictory results. 
According to VEjas (1883)” and JosEPH (1887)*, this method 
demonstrates in the cat and the rabbit the presence of fibers 
which degenerate towards the ganglion after section of the dor- 
sal root, while by the same method Kanter (1884)”, SINGER 
and Minzer (1890), SHERRINGTON (1894)” and (1897)*, VAN 
GEHUCHTEN (1895), and Gasri (1896)” found no evidence of 
such fibers in the cat, dog, or monkey. 
STRICKER (1876)", Bonuzzi (1885 and 1887)”, GARTNER 
(1889), Morar (1892)*, Hasreriik and Bigeprt (1893)*, 
WERZILOFF (1896)", and BayLiss (1900 and 1902)** have 
demonstrated by physiological methods vaso-dilator fibers in 
the dorsal roots of the spinal nerves of the dog. Roux (1900) 
in man in cases of tabes reports the demonstration of degener- 
ated nerve fibers of a small caliber in the ram communicantes. 
In order to determine the location of the trophic centres of 
these fibers Roux sectioned in the cat the dorsal roots of sev- 
