BOTANICAL SOCIETY OF EDINBURGH. 561 



becomes more or less liemispherical in form with a sharply 

 defined outline. At its base a shortly stalked fusion-cell, 

 showing irregularly stellate branching, and arising by the 

 fusion of the auxiliary cell on the one hand with the 

 downward directed cells of the procarp, and on the other 

 with the lowest component cells of the gonimoblast 

 branches, attaches the gonimoblast to a lower cell of one 

 of the wall-forming filaments.^ This fusion-cell, together 

 with some adjoining cells of the gonimoblast branches, 

 remains sterile as a " placenta " (in J. Agardh's sense), but 

 the entire mass of upper cells of the laterally coherent 

 gonimoblast branchlets become fertile, and form a dense 

 reniform mass of tissue, all the cells of which ripen at 

 approximately the same time into spores (in the same way 

 as does the fruit nucleus of G. capillaris). 



The development of the " cystocarps " of G. f areata 

 follows an entirely different course. Procarps like those of 

 E. ccrvicornis are altogether absent. After sporangia have 

 been formed in large numbers in the outer cortex of one 

 of the younger branches of the thallus, and have shed their 

 contents, a number of new structures begin to appear in 

 the inner cortex on the cells of the wall-forming fila- 

 ments, in the inner part of the wall. From any one of 

 these cells, which does not differ at all from the others 

 around it, composing the wall-forming filaments (especially 

 from one of the larger cells of the inner part of the wall), 

 there proceeds asexually a thin cell filament composed of 

 short elements, and resembling a rhizoid. This grows out 

 laterally, and at once gives rise to a copious ramification 

 in the mucilage-containing inter-spaces between the neigh- 

 bouring cells of the cortex. In the small compressed 

 monopodially Ijranched pencil of filaments which arises in 

 this way, one branch, stronger than the others and directed 



1 In older fruiting specimens of Emlotridila cervicornis it seems as if 

 the gonimoblast ^vas attached to the central axis itself. But the 

 younger stages in the development show clearly that the tuft-like 

 procarps arise from the lower or lowest component cells of the wall- 

 forming filaments ; never from the central axis. The accurate examina- 

 tion of the ripe fruit also shows that the gonimoblasts, which arise from 

 the pi'ocarps, and project a considerable distance into the feltwork of 

 interwoven rhizoids filling the central cavity of the shoot, although 

 closely pressed against the central axis, which may even he displaced 

 thereby, are never directly attached, to it. 



