MM. Bornet and Thuret on the Fecundation of the Florideae. 35 



VIII. — On the Fecundation of the Floridese. 

 By E. Bornet and G. Thuret*. 



The fecundation of the spores of the Algae by the antherozoids 

 is a well-known fact, upon which we have now very precise ob- 

 servations. But there still remained a gap to be filled up in the 

 history of the Floridese — one of the highest groups of iMgse, and 

 the most remarkable of all, on account of the number and variety 

 of genera composing it and the peculiarities of their organization. 



Most of the Floridese, as is well known, present two sorts of 

 fructification, upon distinct individuals, — one consisting of spores 

 which divide into fours, tetrasporic fructification; the other, 

 formed by agglomerations of undivided spores, has received the 

 name of capsular or cysfocarpous fructification. We also find, 

 and generally upon different individuals, cellular productions of 

 various forms, composed of small colourless cells, each enclosing 

 a hyaline corpuscle. These organs are designated the anthe- 

 ridia of the Floridese. The corpuscles which they contain are 

 regarded as analogous to the antherozoids of the other Crypto- 

 gamia; but from these they differ considerably, inasmuch as 

 they consist only of a simple globular or oblong vesicle, which 

 is always immobile and destitute of cilia. Their relation to the 

 fructification of the Floridese has hitherto remained entirely 

 unknown. 



They are, nevertheless, certainly fecundating corpuscles ; theix 

 action i^ manifested from the first development of the cystocarp 

 when the latter is still composed only of a small number of cells 

 surmounted by a caducous unicellular hair. Nageli was the first 

 to indicate this transitory structure of the cystocarp in the Cera- 

 mieae, Spyridiese, and Wrangeliese; but, being preoccupied by 

 other views, he never suspected its physiological importance. 

 According to him the capsular fructification is asexual, the 

 tetraspores alone representing the female organ. We hope to 

 show that this is by no means the case, and that the peculiar 

 structure presented by the cystocarp at its origin is destined to 

 facilitate contact with the corpuscles issuing from the antheridia, 

 from which result fecundation and the ulterior formation of 

 the spores. 



Let us take, for example, one of the inferior tribes of the Flo- 

 ridese — that of the Nemaliese, in which the development of the 

 cystocarp is most easily observed on account of its simplicity. 

 If we study the origin of this organ in Helminthora divari- 

 cata, J. Ag., we shall find that it commences by a small cell 

 springing from the side and at the base of one of the dichoto- 

 mous filaments of which the frond consists; this cell elongates, 



♦ Comptes Hindus, Sept. 10, 1866, pp. 444-447. 



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