144 



BOTANY 



Order IV. Cryptonemiales 



In the Cryptonemiales the auxiliary cells are often remote from 

 the carpogonial branch, and from the carpogonium there grow out 



filaments which fuse 

 with the auxiliary 

 cells. This has been 

 especially studied in 

 the genus Dudresnaya 

 (Fig. 114). 



The trichogyne in this 

 genus is extremely long 

 and often twisted. Fer- 

 tilization is effected as 

 usual, and the base of the 

 carpogonium is shut off 

 from the trichogyne. From 

 the carpogonium there 

 now develop two or three 

 slender branches ("sporo- 

 genous filaments"), each 

 of which contains a nu- 

 cleus. The sporogenous 

 filaments may become 

 later divided into two or 

 more cells. 



The auxiliary cells are cells of branches at some distance from the carpo- 

 gonium, and the sporogenous filaments grow until they reach these cells, when 

 fusion takes place between the sporogenous filament and the auxiliary cell. Not 

 infrequently the filament grows, and reaches another, or even two or three other 

 auxiliary cells, but in this case there are as many cells in the sporogenous fila- 

 ment as there are auxiliary cells with which it fuses. 



An enlargement forms at the point of junction of the sporogenous filament 

 and the auxiliary cell (Fig. 114, B), and the upper part of this is cut off by a 

 wall, the nucleus of this cell being derived from the division of the nucleus of the 

 sporogenous filament, and not from that of the auxiliary cell. From this cell, 

 by repeated divisions, arises the mass of spores, so that a single fertilization 

 results here in a number of spore-fruits, which are, however, all connected with 

 the carpogonium by the sporogenous filaments. 



FIG. 113. Polysiphonia sp. A, young cystocarp, in 

 longitudinal section, the spores developing from the 

 group of central cells formed from the auxiliary cell 

 and its neighbors (X 200). B, median section of a 

 ripe cystocarp. 



Corallineae. - In the peculiar family, the Corallinese, very exten- 

 sive cell-fusion follows the fertilization. In Corallina the reproduc- 

 tive bodies are borne in cup-shaped receptacles at the ends of the 

 branches (Fig. 115). A great many carpogonial branches are formed 

 near together, and after fertilization there is a complete fusion of 

 the protoplasts of these branches, as well as of the neighboring cells, 

 nnd from the large multinucleate fusion-cell resulting, the spores are 

 finally produced. 



