orough study of this neutral red method would lead to
important conclusions as to the nature and function of the granules, and
lead us to the most real problems of cell life. With our present
information even we can get definite conceptions founded upon facts, as
to the =biological importance of the cell-granules=.

* * * * *

In his first publication Ehrlich described the =granules as products of
the metabolism of the cells=, deposited within the protoplasm in a solid
form, in part to serve as reserve material, in part to be cast off from
the cell. On the ground of observations on the liver cells, described in
detail in a paper of Frerichs (1883, page 43), Ehrlich gave up this
position, though only temporarily. Ehrlich shewed that the liver cells
of a rabbit's liver, rich in glycogen, appear in dry preparations as
bulky polygonous elements, of a uniform homogeneous brown colour,
surrounded by a thin, well-defined yellow membrane. In cells that were
not too rich in glycogen, small roundish bodies, clearly of a
protoplasmic nature, of a pure yellow, can be seen embedded in the
homogeneous cells that are coloured brown with glycogen. "The hyaline
cellular ground substance, carrying the glycogen, could not under any
circumstances be stained, but the cell-granules above mentioned stained
easily with all kinds of dyes. It was further possible to shew by
staining that the membrane was chemically different from the granules,
since with eosin-aurantia-indulin-glycerine, the membrane stained black,
but the granules orange-red."

To these observations Ehrlich added the following conclusion, "that the
cells of the liver after food really possess a thin =protoplasmic=
membrane, and a homogeneous glycogen-bearing substance, in which the
nucleus and =round granules= (? functionally active) of protoplasm are
embedded.

"On comparing these results with those of more recent investigation of
the cells, it is easy to determine the location of the glycogen very
accurately. Kupffer has shewn, first for the liver cells--and this is
now recognised as generally valid--that their contents do not represent
a microscopically single substance. In the 'survival' preparation he
found, in addition to the nucleus, two clearly distinct substances: a
hyaline ground substance in preponderating amount, and a more scanty,
finely granular, fibrillary substance embedded in it. Kupffer calls the
first paraplasm, the latter p