The structure & development of the mosses and ferns (Archegoniatae) . f these is now divided by twoother intersecting walls, best seen in cross-section (Fig. 45, A),wdiich separate a central cell, nearly tetrahedral in form, fromtwo outer cells. In the complete separation of the centralcell by these first two walls, Porella appears to differ from theother Jungermanniaceae examined,^ where these first twoperipheral cells do not reach to the top of the antheridium, 1 Leitgeb (7), vol. ii. p. 44. lOO xWOSSES AND FERNS CHAP. and a third cell is cut off before the separation of the central-part of
The structure & development of the mosses and ferns (Archegoniatae) . f these is now divided by twoother intersecting walls, best seen in cross-section (Fig. 45, A),wdiich separate a central cell, nearly tetrahedral in form, fromtwo outer cells. In the complete separation of the centralcell by these first two walls, Porella appears to differ from theother Jungermanniaceae examined,^ where these first twoperipheral cells do not reach to the top of the antheridium, 1 Leitgeb (7), vol. ii. p. 44. lOO xWOSSES AND FERNS CHAP. and a third cell is cut off before the separation of the central-part of the antheridium from the wall is complete. It ispossible, too, that in Porella this may be sometimes the antheridium in cross-section at this stage shows twoperfectly symmetrical halves (Fig. 45, A). The two centralcells form a rhomboid surrounded by six cells, the first of theprimary peripheral cells being in each case divided into divisions proceed rapidly in both the central cells and inthe peripheral ones. In the latter they are for a long time. Fig. 44.—Porella Bolanderi (Aujt.). Successive stages of the young antheridium in median longitudinal section, X6oc. always radial, so that the wall remains but one cell thick ; butas the antheridium approaches maturity periclinal walls alsoform in the lower part, which thus becomes double, and atpoints even three cells thick. After the division of eachprimary central cell into equal quadrants, a series of curvedwalls intersecting the inner walls of the peripheral cells arise,and then periclinal walls (Fig. 45, C), but beyond this nodefinite succession of walls could be traced. The development of the spermatozoids is the same as in otherLiverworts. The slender body shows about two complete coils ; IV THE JUNGERMANNIACE^ lOI the vesicle is small, but always present, and the cilia somewhatlonger than the body (Fig. 45, F). The stalk of the antheridiumis long and at maturity composed of two rows of cells. Beforethe c
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