484 THE SALIVAR Y GLANDS. 
The sympathetic nerve-fibres are connected with nerve-cells in the 
superior cervical ganglion. If the cervical sympathetic be cut, the end 
towards the ganglion gives, in about four days, no effect on stimulation, 
but stimulation of the ganglion itself or of the fibres beyond it causes 
secretion and pallor of the gland (p. 522). On microscopical examination, 
the nerve-fibres are found to be degenerated, as far as the ganglion 
but not beyond it. Injection of nicotine causes for a time, varying with 
the dose, effects like those caused by degeneration of the nerve. 1 In 
the cat even 5 mgrms. of nicotine may be sufficient to paralyse the cervical 
sympathetic for a time, but very large amounts, e.g. 500 mgrms., do not 
paralyse the nerves beyond the ganglion. From this and from other 
facts we deduce that the sympathetic fibres are not connected with any 
sympathetic nerve-cells peripherally of the superior cervical ganglion ; 
and there are reasons for believing that they are not connected with 
any nerve-cells between the ganglion and the spinal cord. In the dog 
the cervical sympathetic is much less readily paralysed by nicotine. 
Secretion of saliva produced by stimulation of the medulla 
oblongata. — Bernard 2 found that puncture of the fourth ventricle in 
the dog causes secretion from all the salivary glands, and if the puncture 
be a little above the spot, injury of which produces diabetes, the secre- 
tion may be confined to the submaxillary gland, and from this gland may 
be abundant. Loeb 3 showed that puncture of the medulla caused a greater 
secretion from the submaxillary or the parotid gland, according as the 
puncture was in the region of the nucleus of the ninth or of the seventh 
nerve respectively. With puncture on one side, the effect on the sub- 
maxillary gland of the opposite side was much greater than on the 
parotid of "the opposite side. Griitzner and Chtapowski 4 observed that 
stimulation of the medulla oblongata caused abundant secretion if the 
chorda tympani was intact, a slight secretion if it was cut, but none 
after section of both the chorda and the sympathetic. 
Secretion of saliva produced by stimulation of the cerebral cortex. 
— It is not clear that the cortex of the cerebral hemispheres is connected 
with secretion — or indeed with any visceral phenomenon — in the way 
in which it is connected with the various body movements. 
Stimulation of the motor area, taking the matter broadly, causes 
secretion from the salivary glands, more readily than does stimulation of 
any other part of the cortex. So far as the experiments go, the region 
which causes maximum secretion from the submaxillary gland causes 
also maximum secretion from the parotid. Apparently the secretion 
ceases on cutting the cranial secretory nerve. 
The experiments in which the portions of the cortex which cause 
secretion have been mapped out were made on dogs under curari. 
Those who have experimented on undrugged animals find that stimula- 
tion of the facial area causes no secretion so long as the resulting move- 
ment is confined to the facial muscles, and Eckhard 5 states that the 
secretion of saliva from the submaxillary glands only begins when the 
stimulus is continued long enough, or is made strong enough, to induce 
1 Lansdey and Dickinson, Proc. Roy. Soc. London, 1S89, vol. xlvi. p. 425 ; Langley, 
Jmirn. Physiol., Cambridge and London, 1S90, vol. xi. p. 131. 
2 " Leeons de physiol. experimentale," 1S56, Bd. ii. 
3 Op. cit., supra. 
4 Arch. f. d. gcs. Physiol., Bonn, 1873, Bd. vii. S. 522. 
5 Neurol. Ccntralbl., Leipzig, 1889, p. (35. Cf. also Beitr. ~. Anat. u. Physiol. 
{Eckhard), Giessen, 1876, Bd. vii S. 199. 
