MOSSES. 



323 



in the ventral portion, produces the oosphere from its protoplasmic substance by 

 rejuvenescence, while the axial cells which lie above it become mucilaginous be- 

 fore fertilisation. This mucilage forces the four apical cells (stigmatic cells) of 

 the neck apart, and thus opens the canal of the neck, allowing the antherozoids 

 to penetrate to the oosphere. Fig. 235, B, shows the row of cells of the canal 

 at the period when disorganisation is beginning, and when the stigmatic cells of the 

 neck are still closed. In reference to the morphological significance of the arche- 

 gonia, Leitgeb has already shovrn that at least the first archegonium of Sphagnum 

 arises immediately from the apical cell of the female shoot ; more recently Kiihn 

 found that in Andrea^a the first is formed from the apical cell, the succeeding ones 

 from its last segments, in the same manner as the antheridia of the same genus, 

 and those of Radula and Fontinalis. According to preparations which Schuch 

 obtained in the laboratory at Wiirzburg, the first archegonium arises also in typical 

 Mosses from the apical cell of the shoot. 



The order of succession of the cells in the construction of the archegonium 

 has been studied in detail by Kiihn in the case of Andresea. According to his 

 observations it is in the main similar to that stated by Leitgeb in the case of Radula, 

 although there is a striking discordance in the statements in reference to the forma- 

 tion of the neck and of the row of canal-cells. In Fig. 234 is shown at A the origin 

 of the first archegonium of Andreaea from the apical cell of the shoot ; a septum 

 {?/i m) has already separated the ovoid mother-cell, and a second oblique wall {a a) 

 has divided this into a lower and an upper part ; the former produces, by further 

 divisions, the stalk or base of the archegonium ; from the upper part proceed its 

 neck and ventral portion. While this apical cell is increasing considerably in size, 

 and especially in height, three oblique longitudinal walls (Fig. 234,^, i, 1...2, 2...3, 3) 

 next arise successively, by which a central cell is formed, arched and broader above, 

 and surrounded by a three-celled wall {cf. Fig. 234, C, in transverse section). 

 A septum now separates the upper part of the central cell like a lid, while the lower 

 part is completely enclosed by this and the lateral ones. So far the statements 

 of Kiihn agree with those of Leitgeb in the case of the archegonium of Radula ; 

 but while, according to the latter, the central cell produces both the oosphere and 

 the axial row of canal-cells, the upper ones forming only the stigmatic cells of 

 the neck, and the three lateral ones the wall of the ventral portion and of the neck, 

 Kiihn states, on the contrary, that the upper cell continues to grow as the apical 

 cell, developing successively new stages consisting each of three lateral cells sur- 

 rounding a central canal-cell. Since, how^ever, Kuhn's drawings may be reconciled 

 with the statements of Leitgeb in the case of Radula, it may, perhaps, be assumed 

 that a fresh series of observations would show that after the separation of the first 

 stigmatic cell the axial row is formed entirely from the central cell, the wall of the 

 ventral portion and of the neck entirely from the three first lateral cells. A nearer 

 agreement would thus be indicated not only with the Hepaticae, but also with the 

 higher Cryptogams ^ 



^ [According to Janczewsld (Bot. Zeitg. 1872, p. 869) the archegonia of Mosses possess an 

 apical growtli which is wanting elsewhere in Cryptogams. — Ed.] 



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