, starch seems to be the characteristic
carbohydrate reserve of aquatic, or moisture-loving, species, while inulin
is more common among those which prefer dry situations.

Inulin may be prepared from the tubers of dahlias or artichokes, by boiling
the crushed tubers with water containing a little chalk (to precipitate
mineral salts, albumins, etc.) filtering and cooling the filtrate
practically to the freezing point, which precipitates the inulin.

Inulin is a white, tasteless, semi-crystalline powder, which is soluble in
hot water, from which it may be precipitated by alcohol or by freezing. It
forms no paste like that of starch or dextrin, and gives no color with
iodine. It is levorotatory, and when hydrolyzed by acids or by the enzyme
_inulinase_ yields fructose; in fact, inulin bears the same relation to
fructose that starch does to glucose.

=Graminin, irisin, phlein, sinistrin, and triticin= are all inulin-like
polysaccharides, which have been found in the plants after which they are
named. Their solutions are, as a rule, sticky or gummy in consistency,
which suggests that these compounds bear the same relation to inulin that
dextrins do to starch.

(C) MANNOSANS, OR MANNANS

=Mannan= bears the same relation to mannose that starch does to glucose and
inulin to fructose. It occurs as a reserve food substance in many plants.
It has been reported as present in moulds, and in ergot; in the roots of
asparagus, chicory, etc.; in the leaves and wood of many trees, such as the
chestnut, apple, mulberry, and many conifers; also as a part of the
so-called "hemi-celluloses" which are present in the seeds of many plants,
notably the palms, the elders, cedar, larch, etc.

It is a white, amorphous powder, which is difficultly soluble in water, is
strongly dextrorotatory (specific rotatory power +285 deg.), and when
hydrolyzed yields mannose.

=Secalin= (or carubin) is a substance which is found in the seeds of
barley, rye, etc., which is similar to mannan, but is optically inactive.

(D) GALACTANS

These bear the same relation to galactose that the preceding dextrosans do
to their constituent hexoses. Four different galactans have been isolated
from plant tissues; they are all white, amorphous solids which dissolve
with difficulty in water, forming gummy solutions.

Both galactans and mannans commonly occur associated with cellulose and
hemi-celluloses in the