obscure
the principle of the specificity of each kind of granulation.

A further disadvantage of Altmann's hardening method lies in the
circumstance, that the cell proteids are precipitated by it in a
spherical form, and stain in the subsequent treatment. Hence it is
extremely difficult to distinguish what is preformed, and what is
artefact. Since A. Fischer's publication, where the formation of
granule-like precipitates under the influence of various reagents is
experimentally demonstrated, grave doubts as to the reality of Altmann's
forms have been raised from various quarters. Ehrlich's dry process, on
the contrary, is entirely free from error. Granules cannot be
artificially produced, by desiccation, and the stained appearances
correspond precisely to what is seen in fresh living blood. The greatest
value of the dry method is that the =chemical nature= of the single
granules remains unchanged, so that attempts at differentiation are made
on a nearly unaltered object[22].

Another means of studying the nature of the granules depends on the
principle of =vital staining=. The "vital methylene blue staining"
(Ehrlich) that has since become so important, especially in neurology,
led to the first attempts at staining the granules in living animals.
One of the first publications on this subject is that of O. Schultze,
who placed the larvae of frogs in dilute methylene blue solution, and
after a short period found the granules of the stomach, the red blood
corpuscles and other cells stained blue. This method, however, cannot
pass as entirely free from error, as Ehrlich frequently found that when
the experiment lasts some time the methylene blue often forms granular
precipitates that may be confused with the granules. Teichmann directs a
detailed analysis to this point, and regards most of the granules
described by Schultze as artificial products.

=Neutral red= is highly suitable for the study of vital granule-staining,
a dye recommended by Ehrlich, and employed successfully since that time
by Przesmycki, Prowazek, S. Mayer, Solger, Friedmann, Pappenheim and
others. This dye was prepared by O. N. Witt from nitrosodimethylamin and
metatoluylendiamin, and is the hydrochloric acid salt of a base which is
soluble in pure water, yielding a fuchsin red colour, but which in weak
alkaline solution--the alkalinity of mineral water suffices--is a
yellow-orange hue.

Now neutral red is characterised by a really maximal affinity fo