INTRODUCTION. 



species with this character; but both opinions have been 

 long since given up as untenable. The recent observations 

 of Messrs. Decaisne and Thuret* have shown the existence, 

 in the Fuci, of organs similar in many of their characters 

 to what are supposed to be the male organs of Mosses, 

 Charte, Hepaticcc, &c. The little bodies called by these 

 authors antheridia (a name now adopted) had been previ- 

 ously observed, and referred, under the name acrospores, 

 to the female system of the plant. They are found in the 

 spherical conceptacles of the Fucus, either in those which 

 also contain spores or in others, which they exclusively oc- 

 cupy, and which do not differ from female conceptacles in 

 any other character than by their contents. The antheri- 

 dia are little transparent cases, each formed of a cell, borne 

 on branching threads, that form little tufts springing from 

 the sides of the conceptacle. At maturity the antheridia 

 fall off from their stalks, and then appear more or less filled 

 with orange-coloured granules of very minute size. After 

 a time these granules escape, and immediately commence 

 most lively movements, strikingly similar to those observed 

 in the spores of the Chlorosperms. Under very high pow- 

 ers of the microscope each corpuscle is found to be fur- 

 nished with two active cilia or hairs, which are its organs 

 of motion. The shape of these little bodies is different 

 from that of the spermatozoa found in the supposed anthers 

 of the Mosses and Hepaticee, but their motion by means of 

 cilia is very similar, and there seems no reason to doubt 

 their analogy with those objects. They are best observed 

 in winter, at which season many of the fronds of Fucus 

 serratus and F. vesiculosus will be found covered with 

 orange-coloured or bright yellow receptacles. If some of 

 the brightest coloured fruits are selected and allowed 



* In the ' Anuales des Sciences Naturelles.' 



