in this direction for a series of valuable contributions
to the problem of the actual constitution of the celluloses.

FOOTNOTES:

[1] In this we are confirmed by other writers. See Tollens, _J. fuer
Landw._ 1901, p. 27.

SECTION I. GENERAL CHEMISTRY OF THE TYPICAL COTTON CELLULOSE

(p. 3)[2] ~Ash Constituents.~--It is frequently asserted that silica has a
structural function _sui generis_ in the plant skeleton, having a
relationship to the cellulosic constituents of the plant, distinct from
that of the inorganic ash components with which it is associated. It
should be noted that the matter has been specifically investigated in
two directions. In Berl. Ber. 5, 568 (A. Ladenburg), and again in 11,
822 (W. Lange), appear two papers 'On the Nature of Plant Constituents
containing Silicon,' which contain the results of experimental
investigations of equisetum species--distinguished for their
exceptionally high 'ash' with large proportion of silica--to determine
whether there are any grounds for assuming the existence of
silicon-organic compounds in the plant, the analogues of carbon
compounds. The conclusions arrived at are entirely negative. In
reference to the second assumption that the cuticular tissues of cereal
straws, of esparto, of the bamboo, owe their special properties to
siliceous components, it has been shown by direct experiment upon the
former that their rigidity and resistance to water are in no way
affected by cultivation in a silica-free medium. In other words, the
structural peculiarities of the gramineae in these respects are due to
the physical characteristics chiefly of the (lignified) cells of the
hypodermal tissue, and to the composition and arrangement of the cells
of the cuticle.

_'Swedish' filter papers_ of modern make are so far freed from inorganic
constituents that the weight of the ash may be neglected in nearly all
quantitative experiments [Fresenius, Ztschr. Anal Chem. 1883, 241]. It
represents usually about 1/1000 mgr. per 1 sq. cm. of area of the paper.

_The form of an 'ash'_ derived from a fibrous structure, is that of the
'organic' original, more or less, according to its proportion and
composition. The proportion of 'natural ash' is seldom large enough, nor
are the components of such character as to give a coherent ash, but if
in the case of a fibrous structure it is combined or intimately mixed
with inorganic compounds deposited within the fibres from solution, the
lat