142 THE PHENOMENON OF 



sporangia, in which several resting spores are formed by 

 division of the coat lining the wall, while the contents of 

 the rest of the cells are frequently converted into a 

 ffonidium, which in C. scutata breaks through the upper 

 wall of the cell, and in C. pulvinata emerges laterally, to 

 swarm. The gonidia of this genus appear to possess 

 only two cilia. In the marine Algae of the genera 

 Mesoglcea* and Myrionema, a double, in Ectocarpus\ 

 a triple, fructification has been observed ; but it is very 

 doubtful whether large resting spores occur in these 

 genera, besides active gonidia, since Nageli has pointed 

 out that in Ectocarpus the contents divide into numerous 

 small germ- cells, not only in the roundish apical cells of 

 the branches, but in the longish, many-celled points of 

 the branches, and in the expanding articulation cells of 

 the stem. On the other hand, in the Fucoidea3, (in the 

 strictest sense,) the occurrence of large resting-cells, 

 together with very small swarming- cells, regarded by 

 Decaisne and Thuretj as spermatozoids, is beyond doubt. 

 Both kinds of fructification are formed, in the Fucoidese, 

 in the terminal cells of the jointed filaments which clothe 

 the interior of the fructification cavities. The extremely 

 small gonidia are of pale colour, and have a parietal red 

 point. According to the authors cited, they exhibit two 

 extremely delicate filaments, one in front vibratile, the 

 other, behind, said to be passively swayed about. $ The 



* Kiitzirig, 'Phyc. generalis,' t. xxvii, 1. 



t Vide Crouan ('Ann. des Sc. nat.,' 1839, p. 248, t. v) ; and Nageli, 

 ' Algensysteme,' p. 145, t. ii, f. 1 6. (Also Tlmret, 'Ann. des Sc. nat.,' 

 3 ser., xiv, p. 25, pi. 24. A. H.) 



Decaisue et Thuret, ' Recherches sur les Antheridies et spores des 

 Fucus,' ('Ann. des Sc. nat. i, iii, 1845,) t. i ii. 



The position of the cilia is thus importantly different from that usual in 

 the active gonidia of the fresh-water Algae ; on the other hand, the swarming- 

 cells of the Fucoideae do not agree at all in form with the spermatozoids 

 such as we are acquainted with in the CharaceaB, Mosses, and Ferns. 

 Whether, like the spermatozoids, they are formed in special, minute cellules, 

 or originate by simple division of the contents of the large parent cells, is 

 unfortunately unknown. The character of the contents of the " s warmers" 

 of the Fucoidese renders it unlikely that they possess the power of germi- 

 nating, but it cannot be deduced from this that they have a fertilising action. 



