The röle of tlie cliondriosomes in the cells of the guinea-pig’s pancreas. 267 
and of the empty cells. The process is probably a very gradual one, for 
a ragged margin to that part of the cell adjacent to the lumen, for example, 
(as in the epithelial cells of the secreting mammary gland) is never to be 
seen in the cells of the pancreas. 
It will now be necessary to consider the condition of the nucleus 
during the three phases which have been described. 
The nucleus in the alveolar cells of the pancreas contains as a rule 
a large round nucleolus (Figs. 2 and 6 nu), which may be obscured by the 
presence of chromatin masses adherent to it. The chromatin of the nucleus, 
is usually in the form of four to eight large masses, connected together 
by thin threads of linin (Figs. 4, 6, 10 and 12). 
These chromatin masses, which are of an irregulär outline, are not 
only considerably larger than the largest mitochondria, but differ from 
them also by reason of their irregulär shape. And to the chondriokonts, 
of course, these chromatin masses bear not the slightest resemblance 
whatever. Neither are there any plasmosomes in the nucleus. 
If then a nuclear origin could be traced for the Nebenkern, as many 
authors have claimed for it, we should expect to see structures in the 
nucleus bearing some resemblance to the bodies making up the Nebenkern, 
and if not at any time in the life of the cell, at least during those periods 
wlien the prezymogen material (the ehondriosome) is increasing in volume 
(Fig. 4); and we should also expect to find numerous examples showing 
the extrusion of such bodies from the nucleus into the cytoplasm, with 
the nuclear membrane broken by their passage into the cytoplasm. 
There is not the least evidence of anything of this nature taking place 
in the pancreatic cells of the guinea-pig, and moreover, the passage of 
particles through the nuclear membrane, if it really occurred, could not 
pass unobserved in sections stained with Thionin after Haematoxylin, 
since the nuclear contents are stained with the former dye, in sharp con- 
trast to the deep black of the chondriosomes. Nevertheless, the nucleus 
must take a large share in the work of the cell as the alteration in its 
volume indicates. 
It is smallest at the end of the excretory, and during the rest phases 
(Figs. 8 and 9), and is most voluminous in the middle of the secretory 
phase (Fig. 6). 
Cells of the islets of Langerhans. 
The relation of these cells to those of the alveoli has been the subject 
of much discussion, into which the limits of this paper do not permit me 
to enter. 
Archiv f. Zellforschung. VIII. 
18 
