5 2 o THE SALIVAR Y GLANDS. 
fibres to degenerate is not quite accurately known. Heidenhain states 
that in the dog, stimulation of the chorda causes a secretion three to four 
days after its section, and implies that later than this the nerve has no 
effect. 1 In an experiment on the cat, I - obtained a copious secretion by 
stimulating the cut end of the chorda three days after section ; a secre- 
tion too copious, it seemed to me, to be attributed to the nerve-cells 
which sometimes occur in the region stimulated. But Bradford, 3 three 
days after section of the chordo-lingual nerve near the pterygoid muscle, 
obtained no secretion from stimulation of the nerve up to the point 
where the chorda tympani leaves the lingual. In the dog he found no 
effect five days after section, but no experiment was made at an earlier 
date. It appears, then, that the time required for a loss of irritability 
of the cut chorda tympani in the cat and dog lies somewhere between 
three and five days. 
Notwithstanding the early loss of irritability of the chorda tympani 
after section, stimulation of its nerve-strands near the gland will in the 
cat still cause secretion. In this way I obtained a fairly rapid secretion 
thirteen days after section of the nerve, and a slight secretion in another 
experiment forty-two days after section of the nerve. And Bradford 
obtained secretion from the chorda tympani in the cat up to eleven days 
after section of the chordo-lingual. \\\ his experiments he sometimes 
obtained a secretion by stimulating the chorda immediately after it had 
left the lingual nerve, but sometimes only when the electrodes were 
shifted farther towards the gland. In the dog, five or more days after 
section, he obtained no secretion by stimulating the chorda in any part 
of its course. 
Vulpian 4 noticed in the dog, that a fortnight after section of the 
chorda tympani, injection of extract of jaborandi into a vein gave rise to 
a secretion, though less than normal. Extirpation of the superior 
cervical ganglion at the time of section did not affect the result. In 
the cat, I found that thirteen days after section of the chorda, venous 
injection of a few mgrms. of pilocarpine caused a copious secretion, 
and that forty-two days after section of the nerve, pilocarpine still caused 
a secretion, though distinctly less than on the opposite side. 
These experiments, taken together with those already given on the 
action of nicotine (cf. p. 515), and with our general knowledge of the 
relation of visceral nerve-fibres to nerve-cells, show that, on section of 
the chorda tympani, its nerve-fibres degenerate in three to five days up 
to the peripheral nerve-cells. The nerve-cells are placed chiefly in the 
gland itself — more so in the dog than in the cat. And there can be 
little doubt that the variations observed as the result of stimulating the 
peripheral portions of the chorda depend in the main upon variations in 
the position of the peripheral ganglia. In some animals, postganglionic 
fibres are stimulated when the electrodes are placed on the strands 
outside the gland ; in other animals, this only occurs when the electrodes 
are placed in the hilus. As the gland diminishes in size it naturally 
gives a less copious secretion under the influence of pilocarpine. 
1 Heidenhain (Hermann's "Handbuch," 1880, Bd. vi. S. 88) states that, although there 
was secretion, there was no increased flow of blood. 
2 Journ. Physiol., Cambridge and London, 1SS5, vol. vi. p. 71. 
s Ibid., 1888, vol. ix. p. 304. 
4 Compt. rend. Acad. d. sc, Paris, 1878, tome lxxxvii. p. 350. Before this, Provost had 
stated that muscarine causes secretion after degeneration of the chorda tympani ; cf. Arch, 
dc physio! . norm, etpath., Paris, 1874. p. 719, note. 
