CEdogoniacece 



61 



the female filaments either singly or in chains, each cell being 

 larger than the antheridial cells of the monoecious or dioecious 

 macrandrous species, and known as an androsporangium. The 

 androsporangium is usually produced in the neighbourhood of an 

 oogonium and becomes the mother-cell of a motile ciliated spore 

 known as an androspore, 

 intermediate in size between 

 an antherozoid and a zoogo- 

 nidium. Each androspore 

 swims about for a time and 

 then attaches itself to the 

 female plant, either actually 

 on the oogonium or on some 

 adjacent cell. It then sur- 

 rounds itself with a cell-wall 

 and grows into a very small 

 male plant known as a 'dwarf- 

 male ' or a nannandrium. 

 The dwarf-male usually con- 

 sists of a basal vegetative 

 cell which supports one or 

 more antheridial cells, but 

 occasionally it is reduced to 

 one antheridial cell only. 

 Two antherozoids arise in 

 each antheridial cell as in 

 the ordinary monoecious and 

 dioecious species, and they 

 are set free by the splitting 

 off of a cap if there be only 

 one antheridial cell, or by 



Fig. 13. Dioecious macrandrous species of 

 (Edogonium. A, male plant of (E. rufescens 

 Wittr., from Scilly Is. B, female plant of 

 same. C, female plant of (E. lautumniarum 

 Wittr., from Welsh Harp, Middlesex. D, male 

 plant of same (x460). oo, oogonium; a, an- 

 ther id ium. 



the general dismemberment 

 of the antheridium if there 

 are several antheridial cells. 



When the oosphere is ready for fertilization a hyaline receptive 

 spot appears in it at a point opposite that part of the wall of the 

 oogonium which will open. The oogonium opens in many ways 

 but the method of opening is constant for any one species. Some- 

 times a circular crack is formed, which may be median, superior, 

 or inferior ; sometimes a pore arises either in a superior or inferior 



