8 FIRST GROUP. THALLOPHYTES. 



through a process of growth set up in the carpogone after fertilisation. This process 

 has been already briefly described, but its characteristic features may be again noted 

 in connection with the representation in Fig. 49. The figure shows in / to the left the 

 unicellular procarp, with an elongated filiform upper part, the trichogyne (/), to the 

 summit of which two spermatia are attached. After fertilisation the trichogyne is 

 separated from the carpogone by a transverse septum (Fig. 49, //), and the latter 

 becomes pluricellular by division ; Fig. 49, //, shows one longitudinal wall which has 

 appeared in it. The cells thus formed in the carpogone bulge outwards and form 

 a compact mass of short branches (IV, V, c), which divide into cells that ultimately 

 become carpospores. The trichogyne meanwhile disappears, as Fig. 49, IV and V t 

 show. This cluster of spores, forming a very simple sporocarp (glomerulus), obtains in 

 Batrachospermum a loose envelope by the upward growth of longer cells from beneath 

 the carpogone. 



In the CERAMIEAE, SPERMOTHAMNIEAE, WRANGELIEAE, and other subdivisions of 

 the Florideae the procarp is a multicellular body before fertilisation, and is formed from 

 the terminal cell of a short branch. Spermothamnium hermaphroditum may serve as 

 an example ; Fig. 50, A shows an antheridium (an) of this plant, and to the right of 

 it a procarp with its trichogyne (t). The procarp is in this case terminal, being formed 



ttn 



FIG. 50. Spermothamnium hermaphroditum. A a branch with the procarp (t,f,g, i) and an antheridium an. 

 B after fertilisation, the sporocarp developing. After Nageli. 



from the three terminal cells of a branch. The upper of these (Fig. 50, A, z) and 

 the lower take no part in the formation of the sporocarp, but remain as they were ; 

 the middle cell divides by longitudinal septa into five cells, a central and five peripheral 

 cells. One of these five cells developes into a row of cells (Fig. 50, A,f), which bears 

 the trichogyne (/) on its summit and is therefore called the trichophorej two of the 

 lateral peripheral cells are the carpogenous cells (Fig. 50, A,g). As the two carpo- 

 genous cells are opposite to one another, only one can be seen in the side-view, and 

 the fourth peripheral cell and the central cell have nothing further to do with the 

 development of the sporocarp, but remain stationary. After fertilisation the two carpo- 

 genous cells divide and swell into small roundish heads, on the surface of which numerous 

 crowded spores are formed (Fig. 50, B] ; the origin of these spores from two separate 

 carpogenous cells is, according to Janczewski, no longer recognisable when the cluster 

 of spores is fully formed. In other species of Spermothamnium (Sp. flabellatum) 

 branches shoot out from the cell (c) and surround the sporocarp (cystocarp). 



In other Florideae the branches which surround the fructification are united together 

 into a more or less completely closed envelope, as in Lejolisia. Here the central cell 

 (Fig. 51) of the procarp is the carpogenous cell, while the outer cells develope into 





