PILOCARPINE AND MUSCARINE. 513 
comparatively large dose of atropine. 1 In the dog more than 100 
mgrms. may be injected into a vein, and still secret ion will be obtained 
from the submaxillary gland by stimulating the cervical sympathetic. 
In the cat this nerve ceases to cause a secretion after about 30 mgrms. 
of atropine have been given. 2 
The point of action of atropine is the termination of the nerve-fibres 
around the gland-cells. There are several facts which show this. We 
may mention the following: — In the case of the submaxillary gland, 
when a dose of atropine has been given just sufficient to paralyse the 
chorda- tympani, no secretion is obtained by stimulating peripherally of 
the (true) submaxillary ganglion; i.e., the postganglionic nerve-fibres 
cause no secretion. Atropine applied directly to nerve-fibres — -whether 
preganglionic or postganglionic — in their course towards a tissue, does 
not paralyse them. The paralysis produced by it must then be either 
one of nerve-endings or of gland-cells. But in the case we are consider- 
ing the gland-cells are not paralysed, since they are at once set secreting 
by stimulating the cervical sympathetic. Hence we conclude that 
atropine acts upon and paralyses the nerve-endings of the postganglionic 
secretory fibres of the chorda tympani. And we may conclude, further, 
that in other cases in which atropine paralyses secretory nerves, it has 
this effect in consequence of an action upon the nerve-endings in the 
gland. 
The exact method of action of atropine we can only guess at ; we might 
suppose, either that it annuls the conductivity of the nerve-endings, or that 
it causes a retraction of the terminal filaments, in the manner suggested by 
Duval and others for the processes of nerve-cells in general, so that nervous 
impulses can no longer pass from the nerve-endings to the gland-cells. 
Atropine does not paralyse the vaso-dilator fibres which accompany 
the cranial secretory nerves. This was first shown by Heidenhain 3 in 
the case of the chorda tympani of the dog. It is true that, when large 
doses of atropine are given, both vaso-dilator and vaso-constrictor glandular 
nerves produce less effect than normal, but there is nothing to show that 
this action is in any way specific. 
Pilocarpine and muscarine.— Both pilocarpine and muscarine pro- 
duce copious and prolonged secretion, when given in very small quantity ; 
for example, when 1 or 2 mgrms. are injected into the blood. 4 The 
secretion when it slackens is increased by a further dose of the alkaloid, 
so that the flow of saliva can be kept up for a very long time, apparently 
indefinitely. A large dose is not required in order to produce the 
maximum rate of flow, its effect is rather to increase the duration of the 
flow. The saliva obtained is like that produced by stimulating the 
cerebral nerve, and the secretion is accompanied by a great dilation of 
the vessels of the gland. 
The secretion to which these alkaloids give rise from the submaxillary 
gland is unaffected by section of the chorda tympani, or by extirpation 
of the superior cervical ganglion ; it occurs after the connections of the 
chorda tympani with the local nerve-cells have been paralysed by 
1 Heidenhain, op. cit. 
2 Langley, Jmirn. Physio!., Cambridge, 1878, vol. i. p. 98. 
3 Op. cit., supra. 
4 The chief features of the action of muscarine were described, " Das Muscarin," Leipzig, 
by Schmiedeberg u. Koppe in 1869. 
vol. i.— 33 
