488 THE SALIVARY GLANDS. 
1. Sympathetic stimulated for two and a half hours. The resting gland 
had 25 per cent, of solids, the stimulated gland 23 - 6 per cent. 
2. Sympathetic stimulated for five and a half hours. The resting gland 
had 25 per cent, of solids, the stimulated gland 24*4 per cent. 
We may conclude, then, that during secretion the gland cells 
decrease in weight, and therefore that they increase in weight during 
rest. The increase in rest might be due, as we have said, to a taking up 
of oxygen. But the observations of Pawlow, 1 if they are well founded, 
show that, whether an increase in weight due to oxygen combinations 
occurs or not, there is during rest a not inconsiderable increase in the 
nitrogen of the glands, and this can hardly be due to anything else than 
an absorption of proteids. Pawlow estimated by KjeldahTs method the 
amount of nitrogen in the resting submaxillary gland of the dog on the 
one hand, and in the stimulated gland and in the saliva secreted by it 
on the other hand. He obtained saliva by stimulating the central end of 
the sciatic for one and a half to five hours. In ten (right) stimulated 
glands he found 1-872 grms. nitrogen. In the ten (left) non-stimulated 
glands he found 2T8 grms. of nitrogen. Assuming, then, that the glands 
had the same amount of nitrogen to start with, the stimulated 
glands had lost during secretion about -f of their nitrogen -holding 
substance. In the saliva secreted he found 0416 grms. of nitrogen, 
so that presumably the glands had taken up during secretion about 
- l grin, of nitrogen; this is about gV °f the total amount. The 
numerical results are not such as we should expect from the micro- 
scopical appearances of the gland cells, and it is desirable that the 
experiments should be repeated. 
The general characters of the cells of the lobular ducts suggest that 
they are not simply the lining cells of a conducting tube, but are rather 
active constituents of the gland, concerned either with adding to the 
saliva as it passes by them, or with subtracting from it. There is not, 
however, any clear evidence on the matter. It is true that when a con- 
siderable amount of methvlene-blue is injected into the blood, and the 
glands are excited to secrete, small deep blue particles may be found in 
the duct cells as in the alveolar cells, but methylene-blue is so readily 
taken up by many tissues that little trust can be placed on this as show- 
ing a secretory function. The cells of the lobular ducts contain small 
granules in their outer portion, 2 and, according to Mislawsky and 
Smirnow, 3 these granules decrease during secretion, but it does not 
appear to me certain that the changes described by these authors are not 
due to conditions other than secretory activity. Merkel 4 observed that 
the cells with striated epithelium, i.e. most of the lobular duct cells of 
the submaxillary and parotid glands, stained a deep brown when treated 
with pyrogallic acid in the presence of oxygen. He considered that the 
stain was due to the presence of calcium salts in the cells. This 
naturally suggested that the lobular ducts with striated epithelium might 
secrete calcium salts. But "Werther 5 has shown that the percentage of 
calcium salts in the sublingual saliva of the dog is rather greater than in 
1 Centralbl.f. Physiol., Leipzig a. Wien, 1888, 8. 137. 
2 Langley, Jonrn. Physiol., Cambridge and London, 1S89, vol. x. p. 433. "When the 
grannies of the duet cells swell up and become indistinct, the substance between them takes 
on the characteristic striated appearance seen in hardened specimens. 
3 Arch. f. An«t. it. Physiol., Leipzig, 1896, Physiol. Abth., S. 93. 
4 "Die Speichelrohren," Leipzig, 1S83. 
5 Arch. f. d. gcs. Physiol., Bonn, 1886, Bd. xxxviii. S. 293. 
