350 



MUSCINEM. 



produces the pedicel, the upper one the archegonium itself. The lower cell 

 undergoes numerous transverse and longitudinal divisions into several rows of cells. 

 In the mother-cell of the archegonium there arise three longitudinal walls, by which 

 three outer cells are formed ; these, on their part, enclosing an internal cell which 

 overtops them. The three outer cells are divided by radial longitudinal walls and 

 thus form five or six investing cells ; the median cell is divided by a transverse 

 septum into an upper (stigmatic) and a lower cell. After the whole structure has 

 increased somewhat in length, it comes to consist of two tiers in consequence of the 



Fig. 236.— Later stages in the development of the archegonia and origin of the sporogonium of Marchantia polymorpha ; 

 /, //, young archegonia; ///, IV, after absorption of the axial row of cells of the neck; Kwhen ready for fertilisation; 

 VI-VIII the cells of the mouth of the neck x relaxed after fertilisation ; the fertilised oosphere /"shows its first divisions. In 

 these figures I-V si is the ventral canal-cell which is last converted into mucilage, e the unfertilised oosphere ; // in V-VII 

 the perigynium in process of development; /JT the unripe sporogonium in the ventral portion of the archegonium which has 

 developed into the calyptra ; a neck of the archegonium ; y wall of the sporogonium ; st its stalk (foot) ; inside the sporogonium 

 are the young elaters arranged in rays, among them the spores. (I-VIII X 300, IX about 30.) 



division of each of the six investing cells, like the internal cell, by a transverse 

 septum. The lower tier forms the ventral portion, the upper the neck of the 

 archegonium. The internal cell of the ventral portion, the central cell, increases 

 considerably in size and is divided by a transverse septum into a large inferior cell, 

 the oosphere, and a small upper cell, the ventral canal-cell. Meanwhile the upper tier 

 of cells, the neck of the archegonium, elongates; its axial cell dividing into four, 

 eight, or sixteen long narrow cells, the canal-cells of the neck. Further transverse 



