the grounds of this
observation Ehrlich returned to his original assumption that the
granules are secretory products of the cells, and defined his standpoint
at that time as follows:

"Did the neutrophil granulations really represent the bodies which
supply these cells with oxygen, as Altmann supposes, a condition such as
we have here brought forward would be impossible, since with the
disappearance of the granules death of the cells must follow. But from
the point of view of the secretion theory the condition described is
easily explainable. Just as under certain conditions fat-cells may
completely lose their contents without dying, so the bone-marrow cell,
if the blood fails to yield to it the necessary substances, may
occasionally be unable to produce more neutrophil granules. And thus it
becomes non-granular."

The view, that the granules are special metabolic products of the
specific cellular activity, is strongly supported by the great chemical
differences between them. Ehrlich made these peculiarities clear for the
blood-cells, and found that their granulations differ from one another,
not only in their colour reactions, but also in their =shape= and
=solubility=; so that they must be sharply distinguished.

Whilst for instance the majority of the granules are more or less
rounded forms, in some classes of animals, _e.g._ in birds, the
analogues of the granules of mammalian blood are characterised by a
decided crystalline form, and a strong oxyphilia. The substance of the
mast cell granulations is also crystalline in some species of animals.

The size of the individual granules is constant in any animal species
for every kind of granule--excepting only the mast cells. The eosinophil
granulation reaches its greatest size in the horse, where really
gigantic examples are found.

The presence of granulated colourless blood-cells has been demonstrated
in the most various classes of animals, and even in the blood of many
invertebrates, particularly, as Knoll has shewn, in the
Lamellibranchiates, Polychaetes, Pedates, Tunicates and Cephalopods.
Concerning vertebrates, especially the higher classes, accurate and
ample researches are to hand. In birds we recognise two oxyphil
granulations, of which one is embedded in the cells in the crystalline,
the other in the usual granular form. Amongst the vertebrates most
investigated classes possess granulated polynuclear cells. To this
circumstance Hirschfeld has recently