290 



THALLOPIirTES. 



The ylntheridia are either single cells at the end of long articulated branches, when, 

 as in Batrachospermum, each produces only one antherozoid, or the mother-cells of the 

 antherozoids are congregated together in large numbers on a common axis as the 

 terminal members of a very short branching-system (as in Ceramiaceae). In Nitophyllum 

 they densely cover certain portions of the surface of the thallus which consists of a single 

 layer of cells ; in the Melobesiaceae they are produced in cavities which are formed by 

 the overarching of the surrounding tissue. The roundish antherozoids have no cilia and 

 do not swarm, but are moved along passively by the water; some of them are thus 

 brought into contact with the trichogyne ; they adhere to it, and, in consequence of 

 the absorption of the cell-walls at the points of contact, their contents pass into it. 

 The trichogyne remains otherwise permanently closed. 



According to the structure of the Carpogonium, three types may be distinguished : 

 (i) In the Nemalieae, to which Bat rachospermum belongs^, the entire female organ 

 consists, as in the Coleochaeteae, of a single cell, which is prolonged upwards into a 



Fig. i98.—Ne7vah'on multifidttm ; I a branch with carpogonium c and antherozoids j/ ; //, 

 /// commencement of the formation of the sporocarp ; IV, V development of the cluster of 

 carpospores ; t the trichogyne ; c the carpogonium or sporocarp (after Thuret and Bornet). 



trichogyne (Fig. i88, /, /). After fertilisation the basal portion of the carpogonium 

 becomes multicellular in consequence of divisions having taken place (Fig. i88, //, c). 

 The cells thus formed bulge outwards and give rise to a dense aggregation of short 

 branches {IV, F, c), the terminal segments of which are the carpospores. This simple 

 sporocarp acquires in Batrachospermum a loose investment by the outgrowth of pro- 

 longations from the cells beneath the carpogonium. 



(2) In the Ceramieae, Spermothamniese, Wrangelieae, &c., the carpogonium is a 

 multicellular structure before fertilisation, which has arisen from the terminal cell of 

 a short branch. A lateral row of the cells bears the trichogyne, and is termed the tri- 

 chophore (Fig. 189, A,f). This structure undergoes no further developement after the 

 carpogonium has been fertilised. Certain other cells, however, lying in the neighbour- 



^ As to Lemanea, which probably belongs to this group, see Sirodot, Ann. des Sci. Nat. 

 5® serie, vol. XVI. 1872. [Sirodot (Compt. Rend., 1873 and 1880) has found that the spores of 

 Batrachospermum produce a Chantransia from which again the Batrachospermum is developed.] 



