186 Finer Structure of the Glandula Submavillaris 
the epithelium of the gall bladder, and concluded that the reaction is 
not specific for mucin. Although such reactions, along with the accom- 
panying morphological structure of a large, clear cell, of indifferent 
staining power, and a somewhat flattened nucleus lying in the proximal 
zone of the cell, is suggestive of the mucous nature of these distal tubular 
cells of the rabbit’s submaxillary, we are not warranted in interpreting 
them as such, at least in the light of our present meager knowledge of the 
chemistry of the mucins. The researches of Langley, 86, and Ham- 
marsten, 85, have shown that the elaboration of mucins by the secreting 
cells is a process involving several stages. Mayer, 97, constructed a 
graded series of mucins, ranging from those which stained with difficulty 
in muchematein to mucin which stain readily and deeply with the same 
dye. Conversely he was able to obtain a typical mucin reaction in the 
cells of the gl. submaxillaris of the hedgehog, a gland which, according 
to Krause, does not secrete mucin. Bensley, 02, in a study of the cardiac 
glands of mammals has called attention to the fact that it is unreasonable 
to expect that the different mucins and different stages of the elaboration 
of mucin would present always the same staining properties. It is 
possible that future researches may prove that these cells secrete a mucin- 
like substance. 
The second type of cell is found in the group of granule-containing 
cells in the region of an intercalated duct and presents the well-known 
picture of a serous cell. The cytoplasm is abundant and stains readily 
and deeply with ordinary dyes. ‘The nucleus is prominent, lics towards 
the center of the cell, and is spherical in form. If a ferment were 
elaborated by this gland, it would be natural to conclude that the cells 
of this second type gave rise to it, and that the granules found within 
them were zymogenic in character. From the fact that the granules 
stained black with osmic acid Nussbaum, 77, concluded that these cells 
were particularly rich in an amylolytic ferment and that the distal 
tubular cells were not concerned in its formation. Langley, 78, and 
Griitzner, 78, were unable to confirm his observations and believed that 
an amylolytic ferment was absent from this gland. With Macallum’s, 
95, microchemical test for iron, a negative result was obtained. The 
presence of iron either in the granules or in the cytoplasm could not be 
demonstrated. The nitro-molybdate reaction, employed by Macallum, 98, 
to detect phosphorus microchemically in the tissues, also gave a negative 
result. Prozymogen, either in a diffused form in the proximal zone of 
the cell, or irregularly distributed in the basal cytoplasm in the form 
of “basal filaments” of Solger was accordingly regarded as absent. 
I a ee 
