Fertilization of the Floridez., 27 
in other cases these cells are easily distinguished by their 
remarkable size (Petrocelis, Polyides) ; in other cases, again, 
they become developed into peculiarly-formed thallus-fila- 
ments, and are thus easy to detect in the midst of the sterile 
tissue (Dudresnaya, figs. 18, 20, Dumontia). To these cells, 
which from their subsequent behaviour are also to be called 
auxiliary cells, the ooblastema-threads attach and unite them- 
selves. 
Sometimes (Petrocelis Ruprecht’, Hauck) the apex of the 
ooblastema-thread grows directly to the auxiliary cell and 
attaches itself firmly thereto. By resorption of the separating 
membranes the apical cell itself enters into a conjugation with 
the auxiliary cell. In the majority of cases, however, the 
apex of the ooblastema-thread grows close by the auxiliary 
cell, not unfrequently clinging to it (fig. 18), and then sepa- 
rates as a growing terminal cell (fig. 20). But the newly 
formed joint-cell, which is now applied more or less closely to 
the auxiliary cell, enters into open connexion therewith by the 
development of a shorter or longer conjugation-process. In 
both cases, after the resorption of the separating membranes, 
the plasma-bodies of the auxiliary cell and the ooblastema- 
cell unite to form a single cell-body. 
The further development of this conjugation-cell is, how- 
ever, very different in the various individual cases. In many 
instances (Polyides, Petrocelis, Dudresnaya) the amalgama- 
tion of the two conjugating cells is limited to the union of 
the two protoplasm-bodies into’a single cell-body, while the 
cell-nuclei of the two conjugating cells remain separated, and 
are still to be found within the two halves of the conjugation- 
cell. In these cases a process issues laterally from that half 
of the conjugation-cell which represents the ooblastema-cell, 
and its apex becomes segmented off as a separate cell (fig. 19), 
and then, by further growth, gives origin to a distinct spore- 
complex*. Lastly, in other cases (Gleosiphonia) the two 
conjugating cells fuse together completely, and from the 
ooblastema-cell the whole of the protoplasm, with the cell- 
nucleus, gradually passes over into the auxiliary cell until 
only the external membrane remains (figs. 11,12). Then 
the auxiliary cell becomes separated off as an independent 
* In Dudresnaya coccinea, Crouan, the terminal cell of this process 
does not grow into a spore-complex (as in D. purpurifera, J. Ag.), but it 
develops into a long-jointed cell-filament, which, as a side-branch of the 
ooblastema-thread, diffuses itself in the surrounding tissue. But besides 
this process of the former ooblastema-cell (one or) two ae 
issue from the same cell (fig. 21), which apply themselves laterally to the 
former auxiliary cell, grow and close around it, and then produce a single, 
sometimes indistinctly bilobed spore-complex. 
Ann. & Mag. N. Hist. Ser. 5. Vol. Xlil. ,. 
