. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. MINUTE ANATOMY OF FLO WISHING PLANTS 221. Lalex tubes (/). — TSCHIRCH. (Fig. 372). The cell fusions may take place mainly in longitudinal directions, giving the semblance of jointed tubes, or in all directions, producing a dense net- work. In the Milkweeds and the Euphorbias the milky juice {latex} is held in elongated, branching, tubular sacs originating as single cells in the emln'yo, and growing with the g
. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. MINUTE ANATOMY OF FLO WISHING PLANTS 221. Lalex tubes (/). — TSCHIRCH. (Fig. 372). The cell fusions may take place mainly in longitudinal directions, giving the semblance of jointed tubes, or in all directions, producing a dense net- work. In the Milkweeds and the Euphorbias the milky juice {latex} is held in elongated, branching, tubular sacs originating as single cells in the emln'yo, and growing with the growth of the plant until they have pushed their way into every part of the plant body. The latex itself is a mixture of a con- siderable variety of substances; sometimes some of the ingredients are poisonous, as, for example, mor- phia, the active principle of opium, found in the latex of the Poppy. 513. Tissues. — The word tissue has been frequently used al)ove without exact definition, ^-et probably without misapprehension. Technicall}' the term tissue means a mass or collection of cells of the same kind. Any num- ber of cells of a certain kind constitute a particular kind of tissue. Thus collench3'ma, a jjarticular kind of tissue, was descril)ed al)Ove. 514. Fibrovascular bundles are so called from the fact tliat tliey are made up largely of fibrous cells and vessels (ducts). In a translucent herbaceous stem like that of the Balsam, the bundles may be seen without dissection, as strands hini;' not far beneath the surface, traversino- the entire length of the stem, and giving off branches to the leaves. In the cross section of such a stem these bund'ss wouhl be seen as several—[) five — areas more opaque than the surrounding parenchyma, arranged ap- proximately in a circle (compare Fig. 376). Upon exami- nation with a proper power of the microscope each bundle would Ije seen to consist of three parts (Fig. -373). The inner of these consists largely of wood fib
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