Title: Text-book of botany, morphological and physiological
Identifier: ajp2576.0001.001.umich.edu
Year: 1882 (1880s)
Authors: Sachs, Julius, 1832-1897; Vines, Sydney Howard, 1849-1934. ed. and tr
Subjects: Botany
Publisher: Oxford, Clarendon press
Contributing Library: University of Michigan
Digitizing Sponsor: University of Michigan

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88 MORPHOLOGY OF TISSUES. abundant latex in the bulb-scales of Allium Cepa is found in broad elongated rows of cells, whose broad septa exhibit sieve- or latticed structure, but whose actual per- foration is not quite certain (Fig. 73). Where two tubes of this kind lie side by side, the longitudinal walls also show a pitted structure similar to that of im- mature sieve-tubes. These rows of cells traverse the bulb-scales, at whose base they anastomose, as well as the leaves and scapes, in long nearly parallel rows, which are generally separated from the epidermis by from one to three layers of cells. Similar rows are formed by the Utricular Vessels1 of Amaryllidese, as Narcissus, Leucojum, and Galanthus; they resemble, moreover, laticiferous vessels in this, that the septa of the rows of cells become partially, sometimes entirely, absorbed; but their sap is not milky, and contains numerous needle-like crystals of calcium oxalate (raphides). Allied to these are numerous other structures in Monocotyledons which bear scarcely any other resemblance to laticiferous ves- sels. In some genera of Liliacese, as Scilla, Ornitho- galum, and Muscari, the utricular vessels often consist of short interrupted rows of cells, and in the bulbs themselves larger isolated parenchymatous cells, re- sembling the former in containing raphides. That cells containing raphides may, however, unite into tubes, which resemble morphologically laticiferous vessels, is shown in Commelynaceae. Here rows of cells which are early distinguished from those which surround them by containing raphides arise in the young parenchyma of the fundamental tissue of the internodes and leaves. While their neigh- bours continue to divide, they do not, but re- main unaltered, and their septa are, according to Hanstein, absorbed as the entire organ grows and the cells in consequence elongate. In this man- ner long continuous tubes, filled with raphides of enormous length, are formed from the rows of cells of the fundamental tissue which contain crystals2. As in Monocotyledons we find transitional forms between the imperfect laticiferous vessels of bulb-scales and simple lithocysts which do not contain latex but only raphides; so, on the other hand, Sieve-tubes result from a true coalescence of cells which usually, it is true, contain mucilaginous proteids, but sometimes also latex, as in Acer according to Hanstein, and in Gonvolvulaceae according to Vogel, I.e.3 While true laticiferous vessels are confined to a few natural orders, Sieve-tubes, on the contrary, are apparently an essential constituent of the phloem (bast-portion) of the fibro-vascular bundles. They occur nowhere else, and their morphological structure will therefore be spoken of under the fibro-vascular bundles; we must here speak
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FIG. 73.—Longitudinal section through a bulb- scale of Allium. Cepa; e the epidermis; c the cuticle;./ parenchyma; sg the lat*x of the utri- cular vessel coagulated'by potash solution; q q its septum ; the longitudinal wall which separates the utricular vessel from one lying behind it exhibits a pitted structure. 1 (These vessels were termed 'vesicular' in the 1st edition of this translation. The present rendering, corresponding to the French ' vaisseaux utriculeux,' is a more correct rendering of * Schlauchgefasse,' and expresses the fact that they are composed of rows of cells (utricles) the cavities of which have not coalesced by the absorption of their septa) 2 See Hanstein, /. c.; also in Monatsber. der Berliner Akad. 1859. 3 la addition to the forms of cells already named, latex occurs also in the intercellular passages of many plants, as Rhus, Alisma Plantago, &c, and occasionally in the vessels of the wood, as in Carica, some Convolvulacese, &c. On this subject see Trecul, Compt. rend. vol. LXI, 1865.— Van Tieghem, Ann. des Sci. Nat., 5th ser. vol. VI, 1866.—David, I.e. p. 57.

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