36 MM. Bornet and Thuret on the Fecundation of the Floridese. 



is divided successively by transverse septa, and becomes a very 

 short branchlet composed of four superposed cells. Subsequently 

 the superior cell alone continues its development, and becomes 

 filled with a refringent protoplasm ; soon a small protuberance 

 makes its appearance at the apex, and gradually elongates into 

 a long hyaline hair, v^^hich is often slightly dilated at its extre- 

 mity. At last this hair exceeds the filaments of the frond. It 

 is the essential organ of impregnation ; hence, on account of its 

 importance, we give it the name of trichogyne. When the cor- 

 puscles issuing from the antheridia come into contact with the 

 upper part of this hair, they adhere to it, and several of them 

 are often found fixed at its apex. Then the cell which forms 

 the base of the trichogyne begins to swell and to become divided 

 by septa, and is soon transformed into a small cellular mass 

 which will constitute the young cystocarp. During this time 

 the trichogyne seems to wither ; its membrane becomes destroyed, 

 and disappears by degrees, until no traces of it are to be found, 

 even before the cystocarp has arrived at its complete development. 



In the higher tribes of the Floridese the organization of the 

 cystocarp is more complicated, and the fecundation is not so 

 direct as that just described. Thus in the Callithamniese it is 

 not in the basal cells of the trichogyne, but in two lateral cells 

 that those glomerules of spores known as favellcE are formed 

 after fecundation. In the Rhodomelese, Chondriese, and Dasyese 

 the structure of the little cellular urn, or ceramide, whjch will 

 afterwards enclose the spores, is already well advanced, and its 

 form perfectly recognizable, when one of the superior cells begins 

 to be elongated into a trichogyne. When the cellular tissue is 

 closer, as in Ceramium, Plocamium coccineum, Lyngb., &c., the 

 connexion of the trichogyne with the development of the cysto- 

 carp becomes difficult to follow, on account of the opacity of the 

 frond. Lastly, the very existence of this delicate hair has appeared 

 to us impossible to verify in the plants with thick fronds, such 

 as the Gigartinese, Gracilariese, &c. It is, however, to be pre- 

 sumed that its j)resence is a general fact among the Florideae, 

 since we find it in all those the structure of which adapts them 

 to researches of this kind. And whenever we meet with this 

 organ the essential point is ascertained, that its appearance always 

 precedes that of the spores. 



The moment when the corpuscles of the antheridia adhere to 

 the apex of the trichogyne deserves particular attention ; for a 

 phenomenon then occurs which leaves no doubt as to the im- 

 portance of this contact and the reality of the fecundation. We 

 have, in fact, ia a great many cases been able to see with perfect 

 certainty that at this period a true copulation takes place, and 

 that a direct communication is established between the two 



