Plant-life, with 74 full-page illus., 24 being from photos, by the author and 50 in colour from drawings . oxygen, and sulphur,and green plants elaborate them from water, carbondioxide, nitrates, and sulphur compounds. Proteinsare essential to the growth of both plants and animals,and the latter are dependent upon the supply manu-factured by the former. Then, secondly, there are non-nitrogenous products, the fats and carbohydrates. Thefats contain carbon, hydrogen, and oxygen; they maybe derived from carbohydrates or result from the dis-integration of proteins. Fats (or oils) abound in certain
Plant-life, with 74 full-page illus., 24 being from photos, by the author and 50 in colour from drawings . oxygen, and sulphur,and green plants elaborate them from water, carbondioxide, nitrates, and sulphur compounds. Proteinsare essential to the growth of both plants and animals,and the latter are dependent upon the supply manu-factured by the former. Then, secondly, there are non-nitrogenous products, the fats and carbohydrates. Thefats contain carbon, hydrogen, and oxygen; they maybe derived from carbohydrates or result from the dis-integration of proteins. Fats (or oils) abound in certainseeds, such as linseed, in nuts, and in such fruits as theOlive. Carbohydrates are compounds of carbon, hydro-gen, and oxygen, in which the hydrogen and oxygenoccur in the same proportions as in water (HgO); theyembrace sugar, starch, cellulose, and gum. Starch isan exceedingly important reserve material; it aboundsin tubers, such as potatoes, and in starchy seeds—forexample, rice, wheat, barley. Starch, being insolublein water, is transformed into sugar, which is soluble, Plate XLV. Z^/^^Z ^^::^y^. BUTTERBUR {Petastitei ?vulgaris),Order COMPOSITES. PLANT ALCHEMY 273 when it needs to be translocated. Sugar seems to bethe first product of the chemistry involved in carbonassimilation by the leaf under the influence of light,heat, and chlorophyll, and sugar is probably used byprotoplasts in the manufacture of starch. The solublesugar made in the leaves, in the first place, may probablybe commandeered for immediate use in the leaf andelsewhere, while that in excess of immediate require-ments may be converted into starch, and thus constitutea reserve. Possibly when reserve starch is drawn uponfor nutriment its conversion into soluble sugar is accom-plished by the agency of the ferment known as dias-tase. Human indebtedness to plants that build up astarch reserve in cereal grains is beyond is the most important constituent of cell-walls,and also occurs as a res
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1915
