327 BOTANICAL GAZETTE [april 



are conspicuous in the cytoplasm (fig. 33). The egg protoplast 

 does not lay down a new wall until after fertilization. More than 

 one archegonium in a group may function (fig. 45). 



That the archegonium is of an advanced type is shown by its 

 early development from the initial, its relatively few neck canal 

 cells, its inactive cover cell, the intercalary growth of the neck, 

 and its slender venter. 



Sporophyte 



The first division of the fertilized egg is invariably transverse, 

 and is followed by transverse divisions up to 5-7, the sequence of 

 which could not be determined (figs. 34-36). A vertical wall 

 then appears, intersecting the transverse walls (fig. 37), and 

 followed by another vertical wall at right angles to the first one, 

 so that 4 cells are seen in cross-section. Periclinal walls then 

 appear in the upper part of the embryo and a sterile wall is thereby 

 cut off from the central primary sporogenous cells. The relation 

 of the early divisions of the embryo to the formation of the foot, 

 seta, and capsule could not be determined, but it is certain that the 

 lower half of the fertilized egg contributes to the development of 

 the sporophyte, not merely forming an appendage to the foot. 

 A slender calyptra 3 or 4 cells in thickness is formed from the venter 

 of the archegonium (figs. 35, 38). A simple, bell-shaped involucre 

 develops after fertilization; it slightly exceeds the sporophyte in 

 length (fig. 45). 



The sporogenous tissue is differentiated early in the history of 

 the sporophyte. In the formation of the spore mother cells and 

 elaters, the protoplasts of the sporogenous tissue withdraw from 

 their cell walls (fig. 39), those which are to form spores round out, 

 and both the spore mother cells and young elaters form a new 

 wall as the original walls of the sporogenous mass are dissolved 

 (fig. 40). The spore mother cells and young elaters are derived 

 from the sporogenous cells by the same number of cell divisions. 

 In F. cristula an elater is not homologous with a row of spore 

 mother cells, as in forms with a more highly specialized sporophyte, 

 but with a single spore mother cell. The spore mother cells 

 develop 4 inconspicuous lobes (fig. 42), the reduction divisions 



