384 BOTANICAL GAZETTE [May 
also to the right (B) of the lobe bearing the antheridia are old 
antheridia whose outer walls have broken away. Some sperm 
cells are still present. At the extreme right below a is one of the 
four neck cells of an old archegonium whose venter has become 
brown with age. This same method of antheridial dehiscence is 
shown in fig. 19B. 
On the peripheral meristem young archegonia or antheridia or 
both (figs. 8, 9, 12-19, text figs. 2, 3) develop so long as the meristem 
continues its growth, but are not distributed in any definite way. 
In some individuals only one kind of sex organ will appear through- 
out the entire periphery, while on others certain lobes develop 
archegonia and others antheridia. On still other gametophytes 
archegonia and antheridia occur together (text figs. 2, 3 and figs. 
12, 13, 15, 17), mixed indiscriminately around the entire meristem 
ring on the various thallus lobes. One gametophyte, for example, 
bore eleven sporophytes in various stages of development, fifteen 
active antheridia, and numerous archegonia in all stages, from 
old functionless ones to those still in stages of development. — 
the gametophytes from Tekamah, Nebraska, of the 30 per cent 
bearing young active antheridia 70 per cent also bore sporophytes. 
Those from other localities showed approximately the same 
condition. 
Old ruptured antheridia and old archegonia show within a few 
cells of young active sex organs (figs. 15, 16, 17). When the 
antheridia mature and discharge their sperms, the outer wall 
breaks away, leaving but a slight scar in the tissue. The other 
tissues may or may not push up over this. In the former case the 
walls of the antheridium collapse and show as a brown line between 
the vegetative cells; in the latter case the scar is only a ragged 
break in the periphery (figs. 16, 19). These are recognized with 
difficulty, which no doubt accounts for the apparent absence of old 
antheridia on some of the thalli. On many bearing only archegonia, 
however, it was possible to indentify definitely the scars of old 
antheridia. There were a few actively growing individuals on which 
antheridia were not definitely located. In the case of gametophytes 
bearing large or numerous sporophytes, the tissue was so shrunken 
and broken down that it was often difficult to identify old arche- 
