176 



SECOND GROUP.—MUSCINEAE. 



before fertilisation, is continuous upwards with the wall of the neck, which is of one 

 layer of cells in four to six rows (Fig. 130). The venter and the neck inclose an 

 axile row of cells ; the lowermost of these, which is ovoid in shape and lies in the 

 venter, produces the oosphere out of its protoplasm by rejuvenescence ; the cells 

 above it are converted into mucilage before fertilisation ; the mucilage forces asunder 

 the four uppermost cells of the neck, the lid-cells, and opens the neck-canal which 

 affords the spermatozoids the path to reach the oosphere; Fig. 130 shows the row 

 of canal-cells when disorganisation is beginning and when the lid-cells of the neck 

 are still closed. 



Fig. 129. First stage of development of the arclie^onium 

 ol Andreaea, after Kiihn. A terminal archejjonium formed 

 from the apical cell of the shoot. B after the formation of 

 the lid-cells. C transverse section of the young ventral 

 portion ; bh in A the youngest leaves. 



Fig. 130. Fitnaria kysromelriai. A longitudinal section of the summit of a we.ak female plant ; a archegonia. 

 b leaves. B an archegonium ; * venter with the central cell, li the neck, m orifice still closed : the cells of the axile row 

 are beginning to be converted into mucilage (specimen kept three days in glycerine). C the orifice of the neck of an 

 archegonium after fertilisation with its cell-walls coloured dark red, A magn. loo, B 500 times. 



With respect to the point of origin of the archegonium, it should be observed 

 that the first archegonium of Sphagnum arises from the apical cell of the female shoot, 

 and this is the case too in the typical Mosses. Where there are several archegonia, 

 those that follow the first are formed from the younger segments of the apical cell. 

 In the Mosses as in the Hepaticae the archegonium originates in a superficial cell 

 of the vegetative cone. The cell arches outwards and the projection thus formed 

 is divided by a transverse wall into a lower cell which answers to the stalk in the 

 Hepaticae and into an upper cell, in which two oblique walls inclining in opposite 

 directions are then formed, as in the antheridium. These two oblique cells sub- 

 sequently give rise to the tissue of the venter and of the stalk, which is much larger 



