The functional organization of the parasympathetic secretory innervation of the submandibular gland

1. In cats the hypoglossal and chorda-lingual nerves were cut and their central ends sewn to the peripheral end of the latter nerve. At monthly intervals the sensitivity of the submandibular gland to a secretory agent was then estimated.

2 When the supersensitivity resulting from the decentralization of the gland had been lowered to a constant level acute experiments were made. Electrical stimulation of both nerves caused secretion, which was abolished by ganglion blocking drugs and atropine.

3. Simultaneous stimulation of the nerves at frequencies subliminal for each nerve did not cause any secretion.

4. Stimulation of one nerve at a subliminal frequency did not increase a flow of saliva evoked by stimulation of the other nerve. However, as soon as the secretory threshold was reached, the flow was markedly accelerated, provided it was submaximal.

5. In many cases stimulation of the regenerated chorda fibres at a high frequency caused a flow corresponding to the maximal secretory capacity of the gland. In some experiments this was true for the hypoglossal fibres also.

6. The functional organization of the parasympathetic secretory innervation of the submandibular gland of the cat is discussed in the light of these observations.