. The structure and development of mosses and ferns (Archegoniatae). andcentral cell, but sometimesthis division is omitted, andthe basal cell is absent. Thecover cell divides by the usualcross - walls into the fourprimary neck cells, whichhere all develop alike, and theneck remains straight. Thecomplete neck has about sixtiers of cells. The separationof the neck and ventral canalcells follows in the usualmanner, but occasionally theformer may be divided by atransverse cell wall (, A), although ordinarilythe division is confined to thenucleus. The neck cells havesmall nuclei, and in the
. The structure and development of mosses and ferns (Archegoniatae). andcentral cell, but sometimesthis division is omitted, andthe basal cell is absent. Thecover cell divides by the usualcross - walls into the fourprimary neck cells, whichhere all develop alike, and theneck remains straight. Thecomplete neck has about sixtiers of cells. The separationof the neck and ventral canalcells follows in the usualmanner, but occasionally theformer may be divided by atransverse cell wall (, A), although ordinarilythe division is confined to thenucleus. The neck cells havesmall nuclei, and in the liv-ing state are almost trans-parent, with little chloro-phyll. Small glistening bod-ies, apparently of albumin-ous nature, are often present,and are especially conspicu-ous in material fixed withchromic acid. Kny andLuerssen both speak of the quantity of starch in the axial rowof cells in O. regalis, but in neither 0. cinnamomea nor O. Clay-toniana was this noticeable. As the ^gg approaches maturitythe nucleus becomes large and distinct, and one or two nucleoli. Fig. 197.—^A, Young archegonium of , with the neck canal celldivided by a cell wall; B, a nearly ripearchegonium of the same species, X525. X THE HOMOSPOROUS LEPTOSPORANGIAT^ 355 are present. The chromosomes are not conspicuous, a con-dition that we have seen before is not uncommon in the ^ggnucleus. A curious appearance was noted several times just beforethe archegonium seemed about to open, and after the formationof the ventral canal cell. This was the separation from theupper part of the Qgg of a small body containing what lookedlike a nucleus. Whether this is something analogous to thepolar body found in animal ova could not be determined. When the archegonium opens, the four rows of cells bendstrongly outward, and frequently some of the terminal cellsbecome detached. A large receptive spot is present, and thenucleus is smaller than in the younger o^gg, and contains morechromatin, and usually but a
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
