Text-book of botany, morphological and physiological . inaddition, this arises in a similar manner, and grows up around the first (as inPiperacese, Polygonaceae, &c.). The anatropous ovule may be at first a straight orslightly curved projection of tissue (as in Fig. 366, /), but immediately becomesevidently curved at the spot where the first or the single integument springs from it(Fig. 366, //, ///, IV); the apical part enclosed by the integument then forms the rpz PHANEROGAMS. nucleus, while the subjacent basal part becomes the funiculus. As the integumentsarise, the curvature becomes gradua
Text-book of botany, morphological and physiological . inaddition, this arises in a similar manner, and grows up around the first (as inPiperacese, Polygonaceae, &c.). The anatropous ovule may be at first a straight orslightly curved projection of tissue (as in Fig. 366, /), but immediately becomesevidently curved at the spot where the first or the single integument springs from it(Fig. 366, //, ///, IV); the apical part enclosed by the integument then forms the rpz PHANEROGAMS. nucleus, while the subjacent basal part becomes the funiculus. As the integumentsarise, the curvature becomes gradually stronger, and the nucleus becomes invertedeven beiore the outer integument has entirely developed. This latter is there-fore not formed on the side next to the raphe, but clothes all the free part of theovule, right and left of the raphe (Fig. 366, V, VI, VII). Cramer was the first topoint out that anatropous ovules may originate in another way (and this is probablythe most common case), the ovule developing as a secondary lateral projection. Fig. 366.—/—K// stages of development of the ovule of Orchis militaris (x 550); I—VI seen from the side in longi-tudinal section, VII from the front, the funiculus being behind, VIII a horizontal section of/ ; xx the axial row of cells,the upper one of which becomes the embryo-sac e, f the funiculus, ii the inner, ai the outer integument, K the nucleus,es the micropyle, h an intercellular space : in VII the embryo-sac e has completely replaced the tissue of the nucleus. beneath the apex of the young conical funiculus, and curving backwards subse-quently towards the base of the latter. This inversion takes place while the singleor the inner integument is enveloping the nucleus from the summit of the funi-culus ; the second integument, if there be one, then similarly clothes the free part(see Fig. 367, B, C). Kohne^ has indeed thrown some doubt on the actual lateralorigin of the nucleus, not only in Compositse, but also in Solanum,
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
