372 



BOTANY 



PART II 



are fornuMl in special ilask-shaped depressions termed conceptacles, wliich are 



crowded together below the surface 

 in the swollen tips of the dichotom- 

 ously branched thallus (of. F. scrratus, 

 Fig. 291). The conceptacles of F. 

 lilatycarpus (Fig. 297) contain both 

 Gogonia and antheridia, while F. vesi- 

 culosus, on the contrary, is dioecious. 

 From the inner wall of the concep- 

 tacles, between the oogonia and an- 

 theridia, spring numerous unbranched, 

 sterile hairs or paraphyses, of wliich 

 some protrude in tufts from the mouth 

 of the conceptacle (Fig. 297, jO- I'l^^ 

 antheridia are oval in shape, and are 

 formed in clusters on special short 

 and much-branched filaments (Figs. 

 297, a, 299, 1, 2). The contents of 

 each antheridium separate into a large 

 number of spermatozoids, which are 

 discharged in a mass, still enclosed 

 ■within the inner layer of the anther- 

 idial wall (Fig. 299, 4). Eventually 

 set free from this outer covering, the 

 spermatozoids appear as somewhat 

 elongated, ovate bodies, having two 



lateral cilia of unequal length and a red ej^e-spot. The oogonia (Figs. 297, o, 298) 



-^■iQP>Jy 





Fig. 207. — Fucu-s plati/rnrpiif!. Monoeoious con- 

 ceptacle with oogonia of different ages (o), and 

 clnsters of antheridia (rt) ; ;/, paraphyses. (After 

 Thuret, X eirea 25.) 



«^.' f'y ■'^' -^ .; 



B 



FjC: '2'.iS. — A, Oogoninni, the contents of whicli have divided into tlie eight egg-cells. B, Oogon- 

 ium, from which the contents (C) have been extrnded. i), E, Libeiation of the eight egg-cells. 

 St, stalk-cell ; mes, middle, and emi, inni'v layers of the oogonial cell wall. (AI'Iit Tiii'kkt. 

 From Oi.TMANNs' Alijae.) 



are nearly spherical, and are borne on a short stalk (ionsisting of a single cell. 



