THE S ) r MP4 THETIC NER I E- FIBRES. 483 
gland was suggested before Ludwig'fl discovery of secretory nerves, and was 
definitely stated by Schiff in 1 85 I . 
The course of the nerve-fibres to the parotid gland was also investigated by 
Bernard. He obtained secretion in the dog by stimulating the auriculo- 
temporal bianch of the fifth nerve, and a cessation of reflex secretion by ex- 
tirpation of the otic ganglion. He considered that the secretory fibres came 
from the small superficial petrosal nerve, and that the superficial petrosals 
and the chorda tympani arose from the nervus intermedins of Wrisberg. 
Abolition of the reflex secretion in the rabbit was observed by Schiff on simple 
section of the small superficial petrosal. Loeb found that section of the 
tympanic branch of the glossopharyngeal nerve (i.e. of Jacobson's nerve), or of 
the roots of this nerve in the skull, also abolished the reflex secretion, so that 
the secretory fibres of the small superficial petrosal come from the ninth ami 
not from the facial. And Heidenhain obtained copious secretion on stimulat- 
ing Jacobson's nerve. 
If the secretory fibres of the parotid really arise from the ninth nerve, the 
majority of the early observations form a singular record of inadequate experi- 
ments and hast} r deductions. 
The sympathetic nerve-fibres and the nerve-cells with which 
they are connected.— All the salivary glands receive nerve-fibres from 
the cervical sympathetic. The fibres run from the middle or from the 
lower part of the superior cervical ganglion to the external carotid 
artery, and accompany its branches. On the arteries they form a plexus 
having two main longitudinal strands. The nerve-plexus, though chiefly 
of non-medullated fibres, contains some medullated fibres. In the artery 
to the submaxillary gland of the dog, there are twenty to thirty 
medullated fibres, a few of these being 5 (i to 7 (i in diameter, the rest 
2 (j, to 3-5 >x ; the fibres run past the submaxillary ganglion in the bilus, 
without being, so far as can be seen, connected with it. 
The sympathetic fibres both secretory and vasomotor, for the sub- 
maxillary gland of the dog and cat, arise chiefly from the second thoracic 
nerve, to a less extent from the third, fourth, and to a slight and vary- 
ing extent from the first and fifth thoracic nerves. 1 
Langendorff 2 found that four months after hemisection of the 
spinal cord in the upper cervical region, the cervical sympathetic pre- 
sented its normal appearance. We may conclude, then, that the 
glandular nerve-fibres do not descend from a secretory centre in the 
medulla, and simply make their exit by the upper thoracic nerve roots. 
And there are several grounds for believing that the efferent sym- 
pathetic nerve-fibres issuing from a particular nerve root are the axis- 
cylinder processes of nerve-cells situated in the corresponding segment 
of the spinal cord. 
pathol. du svsteme nerveux," 1858, tome ii. ; Schiff, "Lehrbuch. d. Muskel. u. Xerven- 
physiologie," 1858-1859, S. 393; Czermak, Sitiungsb. d. k. Akad. d. Wissensch., Wien, 
1860, Bd. xxxix. S. 526 ; Beitr. .. Anat. v. Physiol. (Eckhard), Giessen, 1860, Bd. ii. S. 
214 ; 1863, Bd. iii. S. 49 ; Navrocki, Stud. d. jihysiol. Inst, zu Breslau, Leipzig, 1865, 
Heft 4, S. 123 ; Loeb, Beitr. z. Anat. u. Physiol. {Eckhard), Giessen, 1869, Bd. v. S. 1 ; 
Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878, Bd. xvii. S. 15 ; Bernard, " Lecons de 
physiol. operatoire," 1879. 
1 Langley, Phil. Trans., London, 1892, vol. clxxxiii. p. 104. 
-Arch. f. d. ges. Physio!., Bonn, 1894, Bd. lviii. S. 165. Strictly speaking, the 
experiment only shows that the great majority of the nerve fibres of the cervical 
sympathetic have their trophic centre in the spinal cord below the hemisection. If even 
a considerable number of fibres had degenerated, they would have been absorbed in the 
time allowed, and would have left no recognisable trace. 
