136 BOTANICAL GAZETTE [august 



The differences in these antheridia are emphasized by the 

 fact that in the first form (fig. 8) there are two spermatogenous 

 initials, paired as in Jungermanniales; in the second form there are 

 four, arranged in the form of a quadrant (fig. 10), as in Marchanti- 

 ales; and in the third and fourth there is but one spermatogenous 

 initial (figs. 10, 24, 25). 



That the structures described above are developing antheridia, 

 and not archegonia, is evidenced by their position and by the pres- 

 ence of an individual involucre. The antheridia are single and 

 dorsal, while the archegonia are grouped in the terminal pocket. 



Archegonium 



The position of the archegonial group is of considerable mor- 

 phological importance. Campbell, with reference to the work of 

 Janczewski, states: "The archegonia are formed in groups just 

 back of the apex but he [Janczewski] does not seem to have been 

 able to detect any relation between them and the apical cell such 

 as obtains in Aneura, but it is possible that such a relation does 

 exist." As mentioned above, the archegonia are terminal and 

 inclosed in a "pocket," which is formed by a cup-shaped involucral 

 growth. As will be described more fully, the archegonia arise 

 from an apical group of cells, any of which may become an arche- 

 gonium initial. There is no regular succession in the formation of 

 archegonia; apparently old and young organs are indiscriminately 

 intermingled. Since the apical group ceases to function as such 

 after the production of archegonia, P. epiphylla may be regarded 

 as truly acrogynous. The involucre is produced by cells which are 

 cut off laterally by the apical group (fig. 40), and pushed out very 

 much as the wings during the previous period of growth; in this 

 event, however, the lateral cells are forced out on all sides to form a 

 complete inclosure. 



The structure and development of the archegonium conforms, 

 in general, to the characteristic liverwort form. Some specific 

 characters may be noted. 2 "After the archegonial mother cell is 

 cut off it does not divide at once by vertical walls, but a pedicel is 

 first cut off [fig. 31]; after which the upper cell undergoes the 



( ' xmi'i-.i [,i,, 1). II., Mossc ,1111! in 11s. \i",\ N ork 1905 (p. 90). 



