AND GEEMINATION OF ALG.E. 127 



male sexual apparatus of the Floridea;, although they possess 

 so little motile power. As far as regards the antheridian 

 cells of Polysiphonia, the author can only confirm what is 

 stated by Thmet. " 1 noticed," he says, " it is true, a gradual 

 emptying of the originally full antheridia ; but I observed the 

 isolated antheridian cells close to the aiitheridium from which 

 they had escaped, free indeed, though always motionless." 

 Like Thuret and Mettenius, the author has never been able 

 to perceive the cilia described by Derbes and Solier, 



Another question equally important with the discovery of 

 the antheridia^ concerns the existence of organs in the Floridece 

 which are impregnated by the antheridea, ivhose existence has been 

 thus certahdy proved. 



The author has been unable to solve this question, which 

 he proposes as a very interesting subject for botanists residing 

 constantly at the sea-side. He has endeavoured, however, by 

 observation of the germination of tetraspores, and of the con- 

 ceptacular spores of Ceramium rubriirn, to approach its so- 

 lution. 



But few observations upon the germination of the Floridece 

 have been published, and an essential defect pervades the few 

 that have been made, owing to the circumstance that observers 

 have been satisfied with the development of a few cells from 

 the spore, and have not sought to inquire whether the growth 

 proceeding from the spore resembles the parent plant or not. 

 In order to determine this point, those plants are undoubtedly 

 the most favourable whose laws of growth are known, and the 

 author therefore instituted his researches on tlie spores of the 

 species of Ceramium, because he liad investigated the forma- 

 tion of the stem of the Ceramia with the accuracy requisite 

 for an inquiry of the kind. For this purpose, it is sufficient 

 to know, with respect to the mode of development of the 

 Ceramia, that they grow with a terminal cell, from whose 

 continued horizontal division the separate joints arise ; and 

 that the first cells of the so-termed cortical layer arise from 

 the formation of oblique walls which are developed in the 

 cells constituting the joints, in a direction from above and 

 inwards, downwards and outwards ; these first cortical cells 

 then subdivide repeatedly, and tlms constitute the cortical 

 tissue surrounding the central series of cells. 



Now, the tetraspore of the Ceramium in its germination, 

 follows the mode just pointed out, from its first division 

 onwards. It is itself the first apical cell of the future plant, as 

 is shown by its longitudinal multiplication in the same way 

 as the other apical cells, and in the indications of the forma- 

 tion of the cortical cells in the mode above described. The 



