STJM ULA 770 X OF THE S YMPA THE TIC NER VE. 4 95 
Eckhard 1 noticed thai the saliva secreted by the submaxillary 
gland, on stimulation of the sympathetic, was more viscid and con- 
tained a higher percentage of solids than that obtained by stimulat- 
ing the chordo-lmgual. 
Neither from the submaxillary, the sublingual, nor the parotid 
gland of any animal does the sympathetic produce a secretion which 
approaches in amount that which is produced by the cranial nerve 
Unless the gland has been secreting under the influence of the cranial 
nerve, before stimulation of the sympathetic (cf. p. 496), this stimula- 
tion causes secretion of a few drops only, and it may he much less. 
Thus, in the dog, stimulation of the sympathetic for a minute will 
ordinarily produce two or three drops from the submaxillary -land, and 
perhaps halt a drop from the sublingual. 
In most of the earlier experiment upon the parotid gland of the 
dog, either no secret inn was obtained by repeated stimulation of the 
sympathetic, or a total amount not exceeding a few drops. This is, 
however, only a more marked instance of the slow secretion which the 
sympathetic, after the first few stimuli, causes in the submaxillary and 
sublingual glands of the same animal. If the parotid gland, after 
sympathetic stimulation, during which no secretion or a trace only has 
been obtained, he hardened, and sections he cut, the lumina, ductules, 
and duct will lie found distended with secretion. 
The maximum total amount of saliva is obtained by stimulating the 
sympathetic for short periods, with short intervals of rest. Stimulated 
in this way— say, during every other half -minute — the sympathetic will 
give from the submaxillary gland of the dog ^th to ^th of the 
quantity of saliva that would lie obtained by similar stimulation of the 
chorda tympani 
With protracted stimulation the secretion may continue slowly for several 
minutes, but sooner or later it stops. Roughly speaking, and within rather 
narrow limits, the amount of saliva obtained is inversely proportional to the 
duration of the previous stimulus and directly proportional to the length of 
the preceding period of rest. After repeated stimulation of the sympathetic, 
there may be no visible secretion for half a minute to a minute after the 
beginning of the stimulation, and occasionally the slight secretion which 
occurs only begins after the stimulation has ceased. 
Heidenhain, stimulating for a quarter of an hour during each half-hour, 
obtained a secretion from each stimulation for eleven successive hours, i.e. as 
long as the experiment lasted. 
In different glands, and in the same gland in different animals, the 
freedom of secretion of sympathetic saliva compared with that produced 
by the cranial nerve, and the percentage of organic substance in the 
saliva, varies considerably. I have already mentioned that the 
sympathetic causes some secretion from the submaxillary gland, and 
often none from the parotid. Relatively, rather more sympathetic 
secretion is obtained from the glands of the cat and rabbit than from 
those of the dog. The sympathetic saliva from the submaxillary gland 
of the dog contains 1 to 3 per cent, of organic substance, that from the 
1 Adrian and EekharJ, Beitr. z. A vat. v.. Physiol. (Eckhard), Giessen, 1860, Bd. ii. S. 83. 
Bernard, Journ. dc Vanat. et physiol., etc., Paris, 1858, tome ii. (1) p. 657, stated that 
sympathetic saliva was much more viscid than chorda saliva. The sympathetic secretion 
in the sheep and rabbit was noticed by v. Wittich, Virchow's Archiv, 1866, Bd. xxxvii. S. 93. 
