204 SEAWEEDS 



may be straight (Fig. 62, b) or have a spiral twist or 

 two. The carpogonium is situated at the end of a row 

 of usually three or four cells, the carpogonial branch, 

 and the cells of this row immediately adjoining it 

 acquire as a rule special characters. This carpo- 

 gonial branch may be either superficial or within the 

 body of the thallus. Fertilisation takes place by a 

 pollinoid becoming attached to the apex of the pro- 

 jecting trichogyne (Fig. 62, c), and the cell-wall having 

 been resorbed at the point of contact, the contents of 

 pollinoid and trichogyne become united. The nucleus 

 of the pollinoid disappears, and though its fusion with 

 that of the carpogonium has not been observed, it 

 may be inferred from analogous cases that it travels 

 down the trichogyne to the carpogonial nucleus, and 

 unites with it. The cell-wall then thickens at the 

 base of the trichogyne and closes the communication ; 

 and the trichogyne slowly withers. 



The farther development of the fertilised carpo- 

 gonium is very various, but it is to be noted that, 

 unlike the homologous bodies in other Algae, it does 

 not separate itself from its tissue connections, and 

 its original cell-wall remains as its own proper 

 membrane. Its farther development follows certain 

 typical plans characteristic of the groups of Rhodo- 

 phycece, and, while these are described in detail in the 

 proper place, they may be briefly stated as follows. 

 The carpogonium itself may in the simplest case give 

 rise to a tuft of carpospore-bearing filaments; or 

 there grow forth from it several simple or branched 

 ooblastema filaments which conjugate with other cells, 

 auxiliary cells, and as a result of this conjugation 



