40 MINNESOTA BOTANICAL STUDIES. 



physes. The antheridia are more numerous in the lower half 

 of the conceptacle. 



It is usually stated that antheridia in different Fucaceae de- 

 velop on branching hairs. This also is the general rule here. 

 It is not necessarily always the case through, for antheridia 

 can frequently be found not on branching hairs, but on simple 

 pedicel cells (PL XII., Fig. 40). The basal cells sometimes 

 divide and later give rise to branches. 



The antheridial hairs arise as papillae or buds on the walls of 

 the cells that line the conceptacle (Fig. jp). These papillae are 

 soon cut off by transverse walls. The outer cell elongates, 

 divides and the lower of the two cells thus formed sends out a 

 lateral bud near its upper end, which is later cut off by a par- 

 tition. This process may be repeated several times along the 

 main axis and the branches till a branching growth, not very 

 dissected, is produced (Figs. 39, 40, 41). 



The protoplasm of contiguous cells is in communication. 

 Few minute chromatophores are found in these branching hairs. 

 The granularity of the protoplasm is not very great as com- 

 pared with that in the cells which develop the oogones. 



Some of the end cells of the branching hairs increase in size, 

 the nucleus divides into two, four, eight, etc., till about sixty- 

 four nuclei are formed, so it is stated by authorities. In the 

 material studied not so many could be counted, or estimated, 

 only about forty. The nuclear division begins early, and dif- 

 ferent stages are all illustrated in the same section. The nuclei 

 become somewhat smaller by successive division, this being 

 especially noticeable in the earlier stages. 



The antheridial cells are at first slender and somewhat pointed, 

 but as the division within continues the cell becomes more and 

 more rounded, usually oval in outline, slightly tapering at the 

 top. The wall of the antheridium is at first thin. It soon thick- 

 ens and becomes capable of swelling greatly (Figs. 4.0 and 41). 

 The cell contents at first communicate with the basal cells, but 

 later round up and draw away from the dividing wall. The 

 spermatozoids stain quickly. They contain minute chromato- 

 phores. From one to six antheridia were observed on a single 

 branching hair. 



The plants studied for this paper were collected at the Minne- 

 sota Seaside Station by Miss Josephine E. Tilden, of the Uni- 

 versity of Minnesota. Thanks are due to her for them, and 

 also for helpful suggestions given to the writer. 



