166 ERYTHEA. 



refractive than that of the peripheral cells, while in some 

 cases a chromatophore and minute quantities of the 

 starch-like substance before mentioned are present. 

 The cutting-ofiP of the stalk-cells from the peripheral 

 cells constitutes the second stage of antheridial development. 

 In the third stage, division takes place in the stalk-cells. 

 As a result of oblique division of the outer half of these cells, 

 from one to three cells are first cut off. (Fig. 2. f.) These 

 increase in size principally in length, and then divide in a 

 plane nearly parallel with their longest axis. The cells pro- 

 duced by this division repeat the process, until at length there 

 are formed rows of cells which usually radiate outwards in 

 every direction from the stalk-cells. (Figs. 2 and 3.) These 

 cells, to which the term filament-cells may be applied, some- 

 times produce at their apices by horizontal division, secondary 

 filament cells, upon which antheridial mother-cells may be 

 borne, while the stalk-cell frequently gives rise to a secondary 

 filament-cell at its apex. A single antheridial cluster would 

 show (Fig. 4) at this point in its growth, the large stalk- 

 cell surmounted by numerous radiating rows of filament-cells 

 densely filled with finely granular, highly refractive proto- 

 plasm. 



The fourth and final stage of growth is the development of 

 the antheridial mother-cells. (Fig. 5. a.) These are cut off 

 singly or in pairs by horizontal or oblique divisions from the 

 apices of the filament-cells. They may be spherical or some- 

 what cylindrical in shape, and of varyingsize, having a diameter 

 of about 5 fj. and a length of 10 fx to 12 fx. So far as could be 

 ascertained, they contain only finely granular substance of a 

 highly refractive nature, which gives them the glistening 

 appearance, before mentioned, when seen in surface view. 



A summary of the stages of development of the antheridia 

 shows the following points. — 



1. The peripheral cells of the frond become densely filled 

 and swollen with protoplasmic contents. 



2. Antheridial stalk-cells, densely filled with protoplasm 



