706 
MR. J. ]ST. LANGLEY ON THE HISTOLOGY AND 
It may no doubt be objected that no one has seen any such movement in the living 
cells ; but then it is to be remarked that observations on living cells have not been 
numerous, and that no particular cell-granule has been observed to disappear although 
numbers do disappear. 
In the cell-protoplasm there is daring secretion an increase of substance capable of 
reducing osrnic acid. 
In all the cases investigated above we have seen that the protoplasm of the 
“ quiescent ” gland-cells stains very slightly with osmic acid, whilst the protoplasm of 
the active cells stains more or less deeply. 
This is opposed to the observations of Nussbaum, but Nussbaum, I think, directed 
his attention so much to the 'granules contained by the cells that he overlooked the 
r cell-protoplasm. 
I have not been able to satisfy myself of the meaning of this increase in staining- 
power of the protoplasm. Since the granules split up during activity, we might 
imagine that the cells do not at once cast out the whole of the substances formed, but 
retain a certain proportion, and that this diffused throughout the cell causes it to stain 
more than normally with osmic acid. 
There is, however, another way of looking at the fact. Generally speaking, the 
formation of granules goes hand-in-hand with a diminution in the power of staining of 
the cell-substance. In the latter period of digestion, when the granules are increasing 
the cell-substance stains less and less with osmic acid. In Triton tceniatus during the 
rapid increase in the granules which takes place from the fourth to the eighth hour of 
digestion there is a rapid diminution in the staining power of the cell. 
This would indicate that the protoplasm of the cells, in passing through those 
changes which result in the formation of granules, uses up the substance stainable 
with osmic acid. This substance might be either taken up by the cell during secretion 
to be further assimilated, or it might be an integral part of the cell-protoplasm. 
The facts we have at present are, I think, insufficient to allow any satisfactory con¬ 
clusion to be drawn on this point; but whatever the cause of it may be, it is, I think, 
a very general phenomena of cells to stain more deeply with osmic acid during active 
secretion than during rest. I have on a former occasion* pointed out that this is the 
case in the parotid, sub-maxillary, lachrymal, and infra-orbital glands of the Rabbit. 
In parotid and sub-maxillary glands the resting cells treated with osmic acid show 
lightly-stained cell-substance with darker-stained granules ; when the cells are 
similarly treated after a period of secretion the cell-substance is distinctly more 
deeply stained, the depth of staining increasing within certain limits with the length 
of time during which the cells have secreted. 
In the lachrymal and infra-orbital glands the resting cells treated with osmic acid 
* Proc. Royal Soc., vol. xxix., p. 377, 1879 ; Jour, of Physiol., vol. ii., p. 261, 1879. 
