Durand : Marchantia polymorpha 327 



verse division, and those of the venter radial division also {Jigs. 

 48-54). The neck-canal mother-cell now divides transversely into 

 two {Jigs. 55, 56), and then each of these into two, making four 

 neck-canal-cells {Jig. 58). The central cell then divides unequally 

 into a distal ventral canal-cell and the larger egg. The writer 

 does not think that a definite cell-wall is laid down in this last 

 division. If it is, it disappears very soon, for the two cells are 

 separated by a space in almost every instance {fig. 61). As a 

 rule the central cell does not divide until after the four neck-canal- 

 cells have been formed, but quite a number of instances were noted 

 in which it had segmented when only two canal-cells were present 



{fig 57). 



All the parts of the archegonium having been differentiated, 

 further development is in the nature of expansion or enlargement 

 of the parts already formed. Up to this time the organ has been 

 nearly cylindrical, but after the division of the central cell the 

 venter becomes somewhat swollen or thickened owing to the 



enlargement of the egg within {Jigs. 62-65, 68, 69). The cyto- 

 plasm stains very intensely and the nucleus is large and conspicu- 

 ous. The neck elongates by repeated transverse division of the 

 wall-cells, and sometimes becomes very long and curved. The 

 neck-canal-cells elongate and the separating walls soon disappear 

 \figs. 65, 68). While four is the usual number of cells, their 

 nuclei occasionally divide so that six or seven sometimes appear 



(fi 



(A 



the 

 slend 



cells had segmented so that five distinct masses were present. As 

 ne archegonium approaches maturity, the ventral canal-cell and 

 neck-canal-cells become disorganized and coalesce into a 

 er mucilaginous strand in the cavity of the neck. Soon the 

 cover-cells break apart and the mass exudes, leaving an open 

 channel to the egg {fig. 69). The latter becomes nearly spherical 



and stair >s very deeply. No indication of a " receptive spot " was 

 observed. 



Embryo and sporogonium 



The sporogonia of Marchantia develop rapidly. Archegonia 



j* re ready for fertilization in May and fully mature sporogonia may 



e found >n the latter part of June or in July. Part of the material 



Elected for archegonia May 9, 1907, was kept in the laboratory 



