260 
George Arnold 
tion of the secretory granules. The Nebenkern appears to kim to dis- 
solve in the cytoplasm, and by serving as nourishment to the latter, 
indirectly aids the production of the secretion. 
Lastly, Mouret (1895) from his researches on the panereas of sorae 
mammals and of the frog, coneluded that the Nebenkern represented a 
prezymogen substance, from which the zymogen granules arose, and that, 
at the time when the zymogen granules and the fluid of the vacuoles in 
which they he, are about to be extruded from the cell, the quantity of 
the prezymogen material increases. Gradually the thread-like bodies of 
which the Nebenkern is composed, break up into granules, which are 
distributed all through the cytoplasm. They increase in size, and even- 
tually form the true zymogen granules. 
It will be seen that the conclusions arrived at in this work, are largely 
in agreement with those of Mouret. 
Space forbids us to reduce the conclusions arrived at by many other 
workers in the same field, suffice to say they are nearly all mutually eon- 
tradictory, in at least one or more important points, especially in Con- 
nection with the origin of the Nebenkern, and the part played by it in the 
formation of the secretion. 
The knowledge that the Nebenkern or paranucleus is the chondrio- 
some of the pancreatic cells, clears away many of the difficulties which 
liave been set in our path by these confhcting opinions, and we are left 
free to build on those fundamental facts in regard to the structure and 
functions of the pancreatic cells, which were established by the researches 
of Kichard Heidenhain (1875, 1880) and which are so generally accepted 
as to be embodied in text books. 
As is well known, the pancreatic cell, eonsists of two well defined 
zones, an outer basal zone, of a homogeneous aspect, and an inner zone 
of a vacuolated structure, and directed towards the lumen of the alveolus. 
The vacuolation of the inner zone, is generally not easily discernable 
in material which had been treated with fixatives containing osmic acid, 
because it is obscured by the presence of the zymogen granules. In those 
cells, however, from which the granules have been extruded, the vacuola- 
tion is sharply defined. (Fig. 2.) 
A very suitable fixative for this purpose is Zenker's fluid, since, 
the zymogen granules not being fixed by it, the vacuolation is not ob- 
scured (Fig. 1). 
The appearanceof the inner zone does not suggest a reticular structure 
alone, but rather, that this region of the cell is composed of round fluid- 
