480 On the Antheridia and Spores of some Fuci. 



LVII. — On the Antheridia and Spores of some species 0/ Fucus. 

 By MM. J. Decaisne and Gustave Thuret*. 



The existence of sexes in the Algse having been admitted, in our 

 opinion, in the commencement of the last century, from incom- 

 plete observations, we went to the coast of the British Channel, 

 with a view to throw some light upon this obscure point of sci- 

 ence. Having met with various new facts in the course of our 

 observations, we shall point out in a few words the principal re- 

 sults of our researches. Our investigations were principally 

 made on Fucus serratus, vesiculosus, nodosus and canaliculars. 



The first two appeared to us dioecious ; the two others mo- 

 noecious. The conceptacles, in the male individuals, are filled 

 with articulated filaments, which bear numerous antheridia in 

 the form of vesicles containing red granules. These antheridia 

 are expelled by the orifice of the conceptacles; if we examine 

 them with the microscope, we see issue from one of their extre- 

 mities transparent corpuscles nearly pear-shaped, each one in- 

 closing a single red globule ; each one of these corpuscles is fur- 

 nished with two very thin cilia, by means of which it moves with 

 extreme vivacity. 



The analogy of these corpuscles with what have been called 

 the spermatic animalcules of Chara, the Mosses and the Liver- 

 worts, is very remarkable. In Chara, as in the Mosses, in Mar- 

 chantia, Targionia, and the Jungermannm, one of us has ascer- 

 tained the presence of the two locomotive cilia, inserted toward 

 the extremity of a filiform body commonly wound spirally. 



According to these observations, from the promptitude with 

 which the corpuscles of the Fucus decompose and form, at the 

 bottom of the vessel in which they are placed, a layer of inert 

 granules which soon completely disappear, we think we are jus- 

 tified in regarding the vesicles which contain them as analogous 

 to the antheridia of other cryptogamous plants, and we cannot 

 admit the opinion which attributes to these vesicles the functions 

 of sporangia, to the corpuscles those of spores. 



Each spore of the dioecious Fuci is simple, oval or pyriform, 

 covered with a ciliated membrane similar to that of Vaucheria, 

 but we have never remarked any motion in it. 



After their exit from the conceptacles the spores present an 

 extremely curious phenomenon. At first simple and perfectly 

 undivided, they sooner or later separate into eight sporules, which 

 are gradually isolated, become regularly spherical, and finally 

 commence each one to germinate. 



In Fucus nodosus and F. canaliculatus the conceptacles in- 



• From the Comptes Rendus, Nov. 11, 1844. 



