5 14 THE SALIVAR Y GLANDS. 



nicotine, and also after degeneration of the chorda tympani itself (cf. 

 p. 519). The alkaloids therefore stimulate some peripheral structure. 

 And as in the case of atropine, so with pilocarpine and muscarine, it is 

 hardly open to doubt that the nerve-endings of the postganglionic fibres 

 are the points of attack. The nerve-endings of the sympathetic nerve- 

 fibres, on the other hand, are not stimulated by pilocarpine or by 

 muscarine. 



Stimulation of the chorda tympani during the pilocarpine secretion l 

 produces in most circumstances an increase in the rate of flow, but when 

 the secretion is as rapid, or nearly as rapid, as the alkaloid is capable 

 of producing, the chorda has little or no effect. Further, after large 

 doses of pilocarpine have been given, the chorda has also little or no 

 effect ; in the latter case, the apparent paralysing action may be due 

 to the presence of more than one alkaloid in what passes for pilo- 

 carpine. 



Stimulation of the sympathetic during the pilocarpine secretion 

 causes a primary increase in rate, like that of the augmented secretion ; 

 after this there is a slowing, and if the stimulation be strong, there may 

 be a complete cessation of the flow. The slowing effect is less in the 

 submaxillary gland of the cat than in that of the dog, and less in the 

 submaxillary of the dog than in the parotid of the dog. 



The effect of the sympathetic in the last two cases is seen in the following 

 extract from an experiment : 2 



DOG. Pilocarpine Nitrate injected Rise of Saliva in Tubes connected with the 

 Ducts of the Submaxillary and Parotid Glands, taken every thirty seconds, 

 in millimetres. 



Submaxillary . 25 54 9 3 2 1 1 3 11 19 29 32 32 

 Parotid .5920000000000122 



stim. sympathetic 



The mutual antagonism 3 of atropine and pilocarpine (or mus- 

 carine). If atropine, in quantity just sufficient to paralyse the chorda 

 tympani, be injected into a vein of an animal, subsequent injection of 

 pilocarpine or muscarine may or may not cause secretion. In many 

 cases, as the amount of the alkaloid given is increased, death ensues, 

 whilst the secretory nerves are still paralysed by atropine. 



There are two methods by which the antagonistic action of two 

 poisons on the salivary glands may be observed more satisfactorily 

 than by injecting them both into the general circulation. The one is 

 to inject the weaker poison in such a way that it passes through the 

 vessels of the gland without entering the general circulation. The 

 other method is to inject a small quantity of a rather strong solution 

 of the weaker poison into the gland duct. In either case, the stronger 

 poison is injected into the general circulation. 



1 Langley, Journ. Anat. and Physiol., London, 1876, vol. xi. p. 173 ; Journ. Physiol., 

 Cambridge and London, 1878, vol. i. p. 339 ; Gley, Arch, de physiol. norm, et path., Paris, 

 1889, p. 151. 



2 Langley, Journ. PhysioL, Cambridge and London, 1889, vol. x. p. 826. 



3 For the action of physostigmine and its antagonistic action on atropine, cf. Heidenhain, 

 Arch. f. d. ges. Physiol., Bonn, 1872, Bd. v. S. 309, and 1874, Bd. ix. S. 335. For the 

 mutual antagonism of poisons in general, and especially as regards muscarine and atropine, 

 cf. PreVost, Arch, de physiol. norm, etpath., Paris, 1877, p. 801. 



