Text-book of structural and physiological botany . 76. — Laticlferous vessel fromEtiphorbia splcndens, with rod* andbone-shaped granules of starch float-ing in the latex. ( x 250.) in bundles, and take part in the formation of the fibro-vascular bundle as soft bast. Vesicular vessels are distinguished from sieve-tubes bytheir contents and situation. The contents are clear ormilky, but always include bundles of acicular crystals(raphides). Their cells, which are moderately thin-walled The Cell as a Member of a Group, SI (Fig. 75), but otherwise of very various structure, are incontact by their
Text-book of structural and physiological botany . 76. — Laticlferous vessel fromEtiphorbia splcndens, with rod* andbone-shaped granules of starch float-ing in the latex. ( x 250.) in bundles, and take part in the formation of the fibro-vascular bundle as soft bast. Vesicular vessels are distinguished from sieve-tubes bytheir contents and situation. The contents are clear ormilky, but always include bundles of acicular crystals(raphides). Their cells, which are moderately thin-walled The Cell as a Member of a Group, SI (Fig. 75), but otherwise of very various structure, are incontact by their ends, which are either broad or narrow, andoften form great systems of tubes, which are never associatedinto bundles, but run separately and usually in a paralleldirection. They occur only in the outer cortex and in thefoliar organs in most Monocotyledons and in some Dicoty-ledons. Laticiferous vessels are simple or branched tubes, fre-quently anastomosing, or united into a more or less closenetwork (Figs. 76, 77). They always contain a fluid. Fig. 77.—Anastomosing laticiferous vessels from a vein of a leaf of thelettuce. (After Hanstein, x 160.) peculiar to the plant, which is often coloured and frequentlyof a milky appearance, and is called latex. They occur inonly a comparatively small number of plants, usually inthe cortex between the bast-bundles and the wood, butsometimes also in the outer cortex, the pith, and the accompany the fibrovascular bundles into the related to them are the laticiferous cells^ longbranched simple cells, such as occur in the Euphorbiaceae,Moraceae, Asclepiadeae, Aconitum^ &c. The latex of differentplants contains a great variety of substances : gimi, resin, 5 2 Structural and Physiological Botany. albumen, opium (in Papaver somniferuni)^ caoutchouc (inSiphonia elastica^ Isonandra gutta^ and species oiFiciis)^ bone-shaped grains of starch (in tropical species of Euphorbia)^ & laticiferous are often distinguished fro
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