xicotixi:. 
5 J 5 
I have tried both methods 1 in observations on the effects of 
pilocarpine and atropine upon the submaxillary gland of the eat and 
dog. The latter method is much simpler, and seems to me better. An 
experiment, briefly stated, is as follows. A paralysing dose of atropine 
is injected into a body vein. A cannula tilled with ;i 2 to 4 per cent. 
solution of pilocarpine nil rati/ is tied into Wharton's duet, ami 0*1 to 0*25 
per cent, of the solution driven into the gland. This causes a secretion 
of saliva and great increase of blood flow, lasting several minutes, but 
steadily lessening in rate. During the flow of saliva the chorda 
tympani becomes again irritable, and may remain so for a short time 
after pilocarpine has ceased to produce a secretion. As the pilocarpine 
is carried out of the gland by the secretion, by the blood, and by the 
lymph, the atropine continually flowing to the gland in the blood again 
acquires the upper hand, and the nerve-endings become again paralysed. 
With renewed injection of pilocarpine there is renewed transient secre- 
tion and renewed transient irritability of the chorda tympani. And 
the paralysis and recovery may lie repeated many times in an hour. 
It is, however, to he noticed, that if more than the minimal dose of 
atropine be given, more than one injection of pilocarpine may he required. 
Although pilocarpine can instantaneously restore some degree of activity to 
the chorda tympani which has been paralysed by atropine, yet the activity is 
always considerably less than normal. 
In the cat, when the cervical sympathetic has been paralysed by atropine, 
its activity can be restored by injecting pilocarpine into the duct, although 
pilocarpine does not stimulate the secretory nerve endings of the sympathetic. 
Nicotine. — Nicotine causes a brief flow of saliva, followed by a 
temporary paralysis of the cranial and sympathetic fibres 2 up to their 
connections with the peripheral ganglia. 3 We have already described the 
main features of this paralysis in connection with the chorda tympani, 
and in connection with the sympathetic (p. 480). In all the mammals 
which have been experimented on, small doses of nicotine readily pro- 
duce excitatory effects, but the amount required to paralyse the secretory 
and vasomotor preganglionic fibres varies widely in different cases. 
Moreover, the minimal amount required to produce paralysis is not 
precisely the same for fibres of different origin, or for fibres of similar 
origin but different function. In the rabbit and cat the differences are 
not great, the amount required varying from about 5 to about 10 mgrms. 
In these animals about 10 mgrms. of nicotine injected into the blood 
will cause a paralysis of preganglionic fibres lasting about fifteen 
minutes. In the dog, 30 to 40 mgrms. have a similar effect on the chorda 
tympani, in so far that, usually, stimulation of the chorda for about twenty 
seconds causes no secretion ; but in some cases, at any rate, and even 
after larger doses, more protracted stimulation of the chorda induces 
gradually an active and protracted secretion, 4 continuing for some time 
after the cessation of the stimulus. And very large doses may be 
given to a dog without paralysing completely the cervical sympathetic. 
1 Journ. Anat. and Physiol., London, 1876, vol. xi. p. 173 ; Journ. Physiol., Cam- 
bridge and London, 1878, vol. i. p. 339 ; 1880, vol. iii. p. 2. For method of injecting into 
the gland arteries, cf. Heidenhain, op. cit., 1874. 
- Heidenhain, Arch. f. d. ejes. Physiol., Bonn, 1872, Bd. v. S. 316. 
3 Langley and Dickinson, Proc. Hoy. Soc. London, 1889, vol. xvi. p. 423 ; Langley. 
Journ. Physiol., Cambridge and London, 1890, vol. xi. p. 123. 
4 Repeated doses have a tendency to canse in the dog a continuous secretion, 
