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lilac flower and orange flowers; fruits yield the oils of pep- 
per, lemon, caraway and fennel; seeds furnish the oils of 
mustard, wormseed, nutmeg and almonds; while resins give 
us the oils of elemi, mastic, myrrh and frankincense. 
The fixed oils, at least from a commercial standpoint, are 
less numerous than the volatile oils, and those in common use 
are mostly derived from the fruits and seeds of plants; for 
example, olive oil is contained in the fruit of the olive, lin- 
seed oil is contained in the seed of the flax plant, castor oil 
is stored up in the seed of the castor oil plant and cotton oil 
abounds in the cotton seed. Fixed oils differ from volatile 
oils in not completely evaporating when exposed to the air. 
In many cases the by-products resulting during the manufac- 
ture of the various oils are of considerable commercial im- 
portance. Some of these by-products are shown in the cases 
with the oils. 
Plant Constituents. Cases 43 and 44. — This exhibit con- 
sists of a series of alkaloids, acids, glucosides and amaroids, 
albuminoids, resinoids and enzymes. These substances plants 
store up in their tissues, or in the tissues of one or more 
organs, and from them they are extracted for use in all 
branches of the arts, sciences and industries. 
Sugars. Cases 45 and 46.—-Sugar is a very important 
plant-product and it is of vast economic value. Sugar cane 
(Saccharum) is the basis of the world’s sugar supply. The 
juice from the stems of the plant is boiled down and by other 
processes is made into the principal crude products shown in 
the cases and later into the commercial grades of sugar. 
The juices of other plants are also used in making sugar, 
for example, in temperate regions, the sugar beet yields an 
enormous amount, the sap of the maple tree is made into 
maple sugar, while in tropical regions the sap of various 
palms, such as the cocoanut palm and the sugar palm, is 
made into palm sugar. 
Starches. Case 47.—Starch, as in the case of many 
other substances, exists in and is consequently derived from 
the several organs of various plants, for example, the roots 
