. Plants and their uses; an introduction to botany . r of afew typical plants through the various stages of their shall, however, examples exhibiting so wide arange of peculiarities that the student may gain finally acomprehensive view of the vegetable kingdom sufficient foran introduction to more special study. 173. The blue algae (Class Cyanophyceae). Among theuseful plants we have studied the only alga is the so-calledcarrageen or Irish Moss (see page 112), and this, as weshall see, belongs to one of the most highly developed classesof seaweeds. It agrees with the great maj
. Plants and their uses; an introduction to botany . r of afew typical plants through the various stages of their shall, however, examples exhibiting so wide arange of peculiarities that the student may gain finally acomprehensive view of the vegetable kingdom sufficient foran introduction to more special study. 173. The blue algae (Class Cyanophyceae). Among theuseful plants we have studied the only alga is the so-calledcarrageen or Irish Moss (see page 112), and this, as weshall see, belongs to one of the most highly developed classesof seaweeds. It agrees with the great majority of alga,however, in being aquatic and containing chlorophyll, andin being without true stem-, leaf-, or root-members. Before 470 THE BLUE 471 passing to a more detailed examination of the higher algffi itwill be most instructive for us to study some of the simplerforms. About as simple as any are the exceedingly minuteplants which for want of a better name we may call tint-ballalgie (Chroococcus), and which when highly magnified present. Fiu. 305.—-Tint-ball Alga. (Chroococcus turgidus, Tint-ball Family, Chroococ-caceoe). A, plant as ordinarily seen; magnified about 400 inner shaded mass of protoplasm is bluish green, surrounded by atransparent gelatinous envelope. B, same, beginning to divide intotwo plants. C, the division advanced by the formation of a doublewall between. D, the division complete. (Redrawn from Kirchner.)—Found in swamps and on wet rocks throughout the world. the appearance shown in Fig. 305. An individual {A) consistsmerely of a spheroidal mass of rather firm consistency andblue-green color, surrounded by a transparent gelatinousenvelope. Near the center of the mass may be seen underfavorable circumstances a comparatively small, somewhatdenser spot. After the plant is dead, the application of purewater dissolves out a blue substance—called phycocyanin ^—leaving the yellow-green chlorophyll. This in turn if dis-solved out by
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