128 PRINGSHEIM, ON THE IMPREGNATION 



product of its germination is therefore indubitably a young 

 Ceramium. 



But it is otherwise with the conceptacular spore. From 

 this arises a very irregular cellular growth, which in form and 

 mode of origin, exhibits no similarity whatever with the body 

 of the Ceramium. 



From this conceptacular spore is manifestly produced a 

 prothallus (Vorkeim), and it only remains to inquire whether 

 this production is equivalent to the prothalli of Mosses or to 

 the prothallium of Ferns. As the author has often seen the 

 commencement of germination in the still closed conceptacular 

 fruit of the Ceramia, without noticing any entrance into it, it 

 appears to him not improbable that the impregnation of the 

 Floridece takes place in the prothallus arising from the concep- 

 tacular spore ; unless it may be, that the Florideoi with closed 

 conceptacular fruit, may behave differently in this respect from 

 those whose conceptacles have a canal leading into the in- 

 terior. 



Tliough his researches have been very incomplete, he sees 

 reason to believe [with Harvey and Thwaites], that the tetra- 

 spores of the Floridece represent only gemmules of the sexual 

 multiplication, whilst the conceptacular spores are either the 

 true female sexual organs of those plants, or at any rate pro- 

 duce a structure which exercises the female sexual function in 

 some way or another. 



Among the Fucoidece of Agardh, the existence of antheridia 

 in the true Fucacece (^Angiospermew, Kiitzing) is no longer an 

 isolated fact. A second instance of antheridia filled with 

 mobile spermatozoids, in structure and mode of development 

 far more closely resembling the antheridia of Fucus than those 

 observed by Thuret in Cutleria, was discovered by the author 

 two years since in Sphacelaria trihuloides. 



The terminal cell of Sphacelaria, which, during the youth 

 of the branch as a vegetative organ, forms the joints by re- 

 peated horizontal division, when the branch has attained to a 

 certain age, suddenly ceases to divide ; it enlarges consider- 

 ably, and constitutes the organ, closely filled with contents at 

 the apex of the older branches, and which has been termed 

 by algologists the sphacela. Tliis sphacela, which is always 

 terminal, is in fact notliing more than the enlarged terminal 

 cell of the ramule. It is precisely the same also with the ter- 

 minal cells of those peculiarly metamorphosed lateral ramules, 

 which are known as the propagative buds (brutknospen) oi 

 the Sphacelaria, and which are capable of becoming new plants 

 by direct growth. Within this transformed cell on the com- 

 mon branches, as well as on the propagative buds, are after- 



