LIFE HISTORIES OF ALG^ 233 



the conceptacles is covered with more or less branched 

 hairs (paraphyses) , and associated with these hairs are the 

 organs that bear the sperms and eggs. In some species 

 of Fucaceae both sperms and eggs are borne in the same 

 conceptacle, and the plant is, accordingly, monoecious. 

 This is the case with one of the species of Fucus (F. 

 platycarpus). In other species, such as those of Asco- 

 pkyllum and Fucus vesiculosus, sperms and eggs are borne 

 in separate conceptacles, and even on separate plants, in 

 which latter case the species are dioecious. 



213. Gametangia. The organs that bear either kind 

 of gametes (sperms or eggs) are termed gametangia. The 

 female gametangium differs in a very fundamental manner 

 from the complex archegonium of the mosses and ferns, for 

 it consists of only one cell, called the oogonium. The 

 male gametangium, or spermagonium, is likewise unicel- 

 lular, and the wall is composed of two layers, an inner and 

 an outer layer. The spermagonia are in reality modified 

 branches of the hairs that line the conceptacles. The 

 oogonia are not attached to the hairs, but directly to the 

 inner surface of the conceptacle by a short unicellular 

 stalk. 



214. Gametes. The male gametes, or sperms, are 

 formed by successive divisions of the protoplast of the 

 unicellular spermagonium. Like those of the liverworts 

 and mosses, they bear two long cilia, attached to the side. 

 They also possess a pigment body, usually reddish in 

 color. The oogonia of Ascophyllum commonly bear only 

 four eggs, organized out of the protoplast of the oogonium, 

 but in rare cases three or five. In some genera (e.g., 

 Fucus) there are eight eggs. The nucleus of the oogonium 

 cell usually divides into eight daughter-nuclei, but in 



