Text-book of botany, morphological and physiological . ll itself, and from theupper parts of its lateral segments ; the lower parts, together with the ventral seg-ment, are employed in the formation of the perianth. The further development of thearchegonia and antheridia has already been described. In the species examined by Hofmeister the fertilised oosphere is first divided by aseptum, /. e. at right angles to the axis of the archegonium. Only the upper of the twocells, the one towards the neck of the archegonium, becomes further divided; itbecomes the apical cell of the sporogonium, and is
Text-book of botany, morphological and physiological . ll itself, and from theupper parts of its lateral segments ; the lower parts, together with the ventral seg-ment, are employed in the formation of the perianth. The further development of thearchegonia and antheridia has already been described. In the species examined by Hofmeister the fertilised oosphere is first divided by aseptum, /. e. at right angles to the axis of the archegonium. Only the upper of the twocells, the one towards the neck of the archegonium, becomes further divided; itbecomes the apical cell of the sporogonium, and is sometimes again divided transverselyonce or twice before a longitudinal wall makes its appearance in it; the two cells thusformed are finally divided into four apical cells arranged as octants of a hemisphere. The basal portion of the growing archegonium becomes swollen out and pene-trates down into the tissue of the stem, being nourished and firmly enclosed by it (theVaginula). As soon as the young sporogonium consists of a number of cells, its wall. ^lO MUSCINEM. becomes differentiated from the inner tissue which is to form the spores and FruUania it is a single circular disc of cells lying transversely beneath the domeof the young sporogonium from which the vertical elaters, and by further divisions,the mother-cells of the spores arise, a process which reminds one of what occurs inSphagnum. In most true Jungermannieae there is, on the other hand, a column of tissueconsisting of vertical rows of cells (surrounded by the wall of the sporogonium consistingof two layers), out of which the elaters and spores are formed. The elaters lie, inthis case, horizontally, and radiate from the ideal longitudinal axis to the wall of thesporogonium (Fig. 225). In Pellia the inner fertile tissue forms, after the differen-
Size: 1501px × 1665px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
