CRYPTOGAMS 



371 



generation (sporophyte) do not, however, show differences in structure as is the case 

 in the Bryophyta and Pteridophyta. 



Family 2. Fucaceae (**). Asexual 

 reproduction is wanting in this order, 

 while sexual reproduction is distinctly 

 oogamous. The oogonia and antheridia 

 of Fueus are formed in special flask- 

 shaped depressions termed CONCEP- 

 TACLES,' which are crowded together 

 below the surface in the swollen 

 tips of the dichotomously branched 

 thallus (cf. F. serratus, Fig. 302). 

 The conceptacles of F. platycarpus 

 (Fig. 307) contain both oogonia and 

 antheridia, while F. vesiculosiis, ou 

 the contrary, is dioecious. From the 

 inner wall of the conceptacles, be- 

 tween the oogonia and antheridia, 

 spring numerous unbrauched, sterile 

 hairs or PARAPHYSES, of which some 

 protrude in tufts from the mouth of 

 the conceptacle (Fig. 307 p). The 

 antheridia are oval in shape, and are 

 formed in clusters on special short and 

 much-branched filaments (Figs. 307 a, 

 309, 1, 2). The contents of each antheridium separate into a large number of 



Flo. 307. Fueus platycarpus. Monoecious con- 

 ceptacle with oogonia of different ages (o), and 

 clusters of antheridia (a) ; p. paraphyses. (After 

 THURET, x circa 25.) 



f. - " - 



mes 



FIG. 308. A, Oogonium, the contents of which have divided into the eight egg-cells. B, OogonJam, 

 from which the contents (C) have been extruded. D, K, Liberation of the eight egg-cells, st, 

 st;ilk-cell ; mes, middle, and end, inner layers of the oogonial cell-wall. (After THURET. From 

 OI.TM ANNS' A!'j"<.) 



spermatoxoids, which are discharged in a mass, still enclosed within the inner 

 layer of the antheridial wall (Fig. 309, 4). Eventually set free from this outer 



