184 Finer Structure of the Glandula Submavwillaris 
gland stimulated twenty-four hours previously. Here the appearance 
was found to be that of a normal resting gland. In fresh sections all 
of the cells were found loaded with granules. he dark cell areas could 
be readily detected, and were seen to occur regularly around the ductules, 
just as in the unstimulated resting gland. The cells of these areas were 
filled with granules, much larger than those in the cells of the clear 
areas. ‘These latter cells were loaded with small granules of low refrac- 
tive power, and while some of the cells were completely filled, in others 
the granules were found only towards the lumen of the tubule. The 
nuclei in most of the cells were not visible, owing to the mass of granules. 
When distinguishable, they were found close to the base of the cell, and 
were spherical in form. There was no evidence in the gland of degen- 
erative processes. In a fixed and stained specimen, taken from this 
stage (Fig. VI), there could be observed little or no deviation from the 
appearance of a normal resting gland. The cells of the dark areas, 
occurring around the ductules, were found loaded with granules, while 
the granules in the cells of the clear areas remained unfixed, just as in 
the normal gland. 
DISCUSSION. 
After an examination of the different physiological phases of the gl. 
submaxillaris of the rabbit, conducted in the manner described, and a 
study of the morphology and microchemical reactions of the cells of 
the gland, one is forced to abandon the view held by some earlier observers, 
that it is a pure serous gland formed of cells of one and the same type. 
The following observed facts justify us in regarding it as a composite 
gland with at least two kinds of cells in the secreting tubules, and further- 
more, that these two varieties of cells do not represent different secretion 
phases of the same cell but are morphologically and physiologically 
distinct: 
(1). In fresh sections of the gland, two distinct areas can be observed, 
each composed of a group of cells containing granules with a refractive 
index different from that of the granules in the cells of the other group, 
indicating a difference in chemical composition. The granules in the 
cells of the two groups behave in a different manner towards various 
reagents. 
(2). The cells forming the “ dark” areas in hardened sections always 
contain granules and are always associated in close relation with an 
intercalated duct. In such fixed and stained specimens the distal group 
of cells, composing the “ clear” areas are always destitute of granules. 
