698 PHYSIOLOGY OF DIGESTION AND SECRETION. 



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 

 are really intercalated in the course of the fibers to the sublingual 

 gland, while the nerve cells with which the submaxillary fibers make 

 connection are found chiefly in the hilus of the gland itself. 



Paralytic Secretion. A remarkable phenomenon in connection 

 with the salivary glands is the so-called paralytic secretion. It has 

 been known for a long time that if the chorda tympani is cut the 

 submaxillary gland after a certain time, one to three days, begins to 

 secrete slowly, and the secretion continues uninterruptedly for a long 

 period as long, perhaps, as several weeks and eventually the gland 

 itself undergoes atrophy. Langley states that section of the chorda 

 on one side is followed by a continuous secretion from the glands 

 on both sides; the secretion from the gland of the opposite side he 

 designates as the antiparalytic or antilytic secretion. After section 

 of the chorda the nerve fibers peripheral to the section degenerate, 

 the process being completed within a few days. These fibers, how- 

 ever, do not run directly to the gland cell; they terminate in end 

 arborizations around sympathetic nerve cells placed somewhere along 

 their course, in the sublingual ganglion, for instance, or within the 

 gland substance itself. It is the axons from these second nerve units 

 that end around the secreting cells. Langley has accumulated some 

 facts to show that within the period of continuance of the paralytic 

 secretion (five to six weeks) the fibers of the sympathetic cells are 

 still irritable to stimulation. He is inclined to believe, therefore, that 

 the continuous secretion is due to a continuous excitation, from some 

 cause, of the local nervous mechanism in the gland. On the histo- 

 logical side it is stated * that after section of the chorda the resulting 

 degenerative changes affect only the cytoplasm, while after the 

 section of the sympathetic the nuclei of the cells are affected, and 

 indeed to some extent on the sound as well as on the injured side. 



Normal Mechanism of Salivary Secretion. Under normal 

 conditions the flow of saliva from the salivary glands is the result 

 of a reflex stimulation of the secretory nerves. The sensory fibers 

 concerned in this reflex must be chiefly fibers of the glossopharyngeal 

 and lingual nerves supplying the mouth and tongue. Sapid bodies 

 *Gerhardt, " Archiv f. die gesammte Physiologie, " 97, 317, 1903. 



