FUCUS. 



[ 278 ] 



FUNARIA. 



the internal one is expelled from the outer 

 like the epispore from the sporange, and 

 finds its way out from the pore of the con- 

 ceptacle. The spermatozoids which fill up 

 the central part begin to move actively, and 

 the sac soon bursts at one or both ends to 

 discharge them. The spermatozoids (fig. 

 259) are excessively minute, transparent bo- 

 dies, scarcely 1-5000" long, enclosing a gra- 

 nule of an orange-colour in most spores, but 

 greyish in F. canaliculatus. The spermato- 

 zoids have two cilia, of unequal length, one 

 directed forwards, the other backwards ; the 

 form of the spermatozoids and the direction 

 of the cilia vary in different species ; the one 

 directed forward usually moving with great 

 rapidity, and producing locomotion, while 

 the other trails behind like a rudder. 



The most interesting and important point 

 connected with the genus Fucus is the pro- 

 cess of fecundation, which has been distinctly 

 made out by Thuret, showing the existence 

 of sexes in the Algae, at least in one fa- 

 mily. 



When a drop of (sea-) water containing 

 active spermatozoids is added upon a slide, 

 upon which the free spores above described 

 have been previously placed, the whole ope- 

 ration of the fertilization may be traced 

 under the microscope. The spermatozoids 

 attach themselves in great numbers to the 

 spores, and by the motion of the cilia com- 

 municate to them a rotatory movement, often 

 very rapid. The field of the microscope 

 becomes covered with these large brownish 

 spheres bristling with spermatozoids, and 

 rolling in all directions among the crowd 

 of those still unattached. After about half 

 an hour, the movement of the spores ceases; 

 the spermatozoids move for some time longer. 

 On the next day such fertilized spores will 

 be found coated with a membrane, the pre- 

 sence of which is readily made out by placing 

 the spore in syrup, which causes the granular 

 contents to contract and shrink away from 

 the envelope, which, moreover, may be co- 

 loured blue by sulphuric acid and iodine. 

 The spore then begins to enlarge and grow 

 by cell-division, one end becoming elongated 

 into a transparent filament like a radicle 

 (fig. 260) ; several more of these are after- 

 wards formed as the upper part grows, and 

 they become organs of attachment by which 

 the young frond is fixed to a stone or other 

 support. The above description corresponds 

 in all essentials to the process as it occurs in 

 the other species. The spores of F. vesicu- 

 losus have been fertilized with spermatozoids 



of F. serratus by Thuret, but no other ex- 

 periments of hybridation succeeded. 



Fig. 260. 



F. serratus. 



Fig. 260. Spores of F. serratus in various stages of 

 germination. Magnified 100 diameters. 



One or two other points deserve notice. 

 The orange spot of the spermatozoids is co- 

 loured blue by sulphuric acid (like CHLORO- 

 PHYLL). Sugar and sulphuric acid colour 

 the spermatozoids red (PROTEINE). The 

 membrane of the sporange (perispore] is co 

 loured blue by sulphuric acid and iodine 

 (CELLULOSE), but this is not the case with 

 the epispore nor the internal membrane, even 

 after treatment with caustic potash. In F. 

 canaliculatus, however, there is a laminated 

 coat immediately surrounding the spores, 

 which, when placed in sea-water, separate, 

 while the coat swells and forms a kind of ge- 

 latinous envelope, which appears as if covered 

 with cilia; these pseudo-cilia appear to be 

 analogous to the similar appearances in the 

 gelatinous sheaths of DESMIDIACE^E and 

 other CONFERVOIDS. 



The months from December to March are 

 the most favourable for observing the above 

 phenomena. No covering glass must be 

 used on the slide, unless prevented by a thin 

 glass support from pressing on the spores 

 and deforming them. A power of 150 to 200 

 diameters suffices for most of the observa- 

 tions ; for the spermatozoids and the actual 

 fecundation, a power of 300. Sea-water must 

 always be used. The germination of the 

 spores may be observed by placing them on 

 glass slides moistened with sea-water, and 

 keeping them under a bell-glass standing in 

 a dish containing sand moistened with sea- 

 water. 



BIBL. Harvey, Br. Marine Alg. p. 18. pi. 

 1 D', Phyc. Brit. pi. 47. 52. 158. 214 ; Gre- 

 ville, Alg. Brit. pi. 181; Decaisne and Thu- 

 ret, Ann. des Sc. nat. 3 ser. iii. p. 5 ; Thuret, 

 ibid. xvi. p. 6, 4 se'r. ii. 197. 



FUNARIA, Schreb. A genus of Funa- 

 riaceas (Acrocarpous Mosses), the common 



