762 PHYSIOLOGY OF DIGESTION AND SECRETION. 



rest, as in the case of the goblet cells of the intestine. In the 

 mucous as in the albuminous cells observations upon pieces of 

 the fresh gland seem to give more reliable results than those upon 

 preserved specimens. Langley* Jhas shown that in the fresh 

 mucous cells of the submaxillary gland numerous large granules 

 may be discovered, about 125 to 250 to a cell. These granules 

 are comparable to those found in the goblet cells, and may be 

 interpreted as consisting of mucin or some preparatory material 

 from which mucin is formed. The granules are sensitive to re- 

 agents; addition of water causes them to swell up and disappear. 

 It may be assumed that this happens during secretion, the gran- 

 ules becoming converted to a mucin mass which is extruded from 

 the cell. 



Action of Atropin, Pilocarpin, and Nicotin upon the Secre- 

 tory Nerves. The action of drugs upon the salivary glands and 

 their secretions belongs properly to pharmacology, but the effects 

 of the three drugs mentioned are so decided that they have a 

 peculiar physiological interest. Atropin in small doses injected 

 either into the blood or into the gland duct prevents the action of 

 the cerebral autonomic fibers (tympanic nerve or chorda tympani) 

 upon the glands. This effect may be explained by assuming that 

 the atropin paralyzes the endings of the cerebral fibers in the glands. 

 That it does not act directly upon the gland cells themselves seems 

 to be assured by the interesting fact, that, with doses sufficient to 

 throw out entirely the secreting action of the cerebral fibers, the 

 sympathetic fibers are still effective when stimulated. Pilocarpin 

 has directly the opposite effect to atropin. In minimal doses it 

 sets up a continuous secretion of saliva, which may be explained upon 

 the supposition that it stimulates the endings of the secretory fibers 

 in the gland. Within certain limits these drugs antagonize each 

 other, that is, the effect of pilocarpin may be removed by the sub- 

 sequent application of atropin, and vice versa. Nicotin, according 

 to the experiments of Langley, f prevents the action of the secretory 

 nerves, not by affecting the gland cells or the endings of the nerve 

 fibers around them, but by paralyzing the connections between the 

 nerve fibers and the ganglion cells through which the fibers pass on 

 their way to the gland, that is, the connection between the pre- 

 ganglionic and postganglionic fibers. If, for example, the superior 

 cervical ganglion is painted with a solution of nicotin, stimulation 

 of the cervical sympathetic below the gland gives no secretion; stim- 

 ulation, however, of the fibers in the ganglion or between the ganglion 

 and gland gives the usual effect. By the use of this drug Langley is 

 led to believe that the cells of the so-called submaxillary ganglion 



* "Journal of Physiology," 10, 433, 1889. 



t "Proceedings of the Royal Society," London, 46, 423, 1889. 



