to show that a very close relation subsists between the different
substances just described. Indeed, with the exception of vegetable
caseine, they may be said all to present the same composition; and, as
already mentioned, there are analyses of it which would class it
completely with the others. While, however, the quantities of carbon,
hydrogen, nitrogen, and oxygen are the same, differences exist in the
sulphur and phosphorus they contain, and which, though very small in
quantity, are indubitably essential to them. Much importance has been
attributed to these constituents by various chemists, and especially by
Mulder, who has endeavoured to make out that all the albuminous
substances are compounds of a substance to which he has given the name
of _proteine_, with different quantities of sulphur and phosphorus. The
composition of proteine, according to his newest experiments, is--

Carbon 54.0
Hydrogen 7.1
Nitrogen 16.0
Oxygen 21.4
Sulphur 1.5
-----
100.0

and is exactly the same from whatever albuminous compound it is
obtained. Although the importance of proteine is probably not so great
as Mulder supposed, it affords an important illustration of the close
similarity of the different substances from which it is obtained, the
more especially as there is every reason to believe that the different
albuminous compounds are capable of changing into one another, just as
starch and sugar are mutually convertible; and the possibility of this
change throws much light on many of the phenomena of nutrition in plants
and animals. Indeed, it would seem probable that these compounds are
formed from their elements by plants only, and are merely assimilated by
animals to produce the nitrogenous constituents they contain.

_Diastase_ is the name applied to a substance existing in malt, and
obtained by macerating that substance with cold water, and adding a
quantity of alcohol to the fluid, when the diastase is immediately
precipitated in white flocks. It is produced during the malting process,
and is not found in the unmalted barley. Its chemical composition is
unknown, but it is nitrogenous, and is believed to be produced by the
decomposition of gluten. If a very small quantity of diastase be mixed
with starch suspended in hot water, the starch is found gradually to
dissolve, and to pass first into the state of dextrine, then into that
of sugar