FUCUS. 



[ 341 ] 



FUNAEIACE^E. 



most spores, but greyish in F. canaliculatus. 

 The sperrnatozoids have two cilia, of un- 

 equal length, one directed forwards, the 

 other backwards ; the form of the sperma- 

 tozoids and the direction of the cilia vary 

 in different species, the one directed for- 

 ward 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 

 process of fecundation. 



When a drop of sea-water containing 

 active spermatozoids, is added to a slide 

 upon which the free spores above described 

 have been previously placed, the whole 

 operation 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 Held of the micro- 

 scope becomes covered with these large 

 brownish spheres bristling with spermato- 

 zoids, 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. In a few minutes after 

 the contact of the spermatozoids, such fer- 

 tilized spores will be found coated with a 

 membrane, the presence of which is readily 

 made out by placing the spore in syrup, 

 which causes the granular contents to con- 

 tract and shrink away from the envelope, 

 which, moreover, may be coloured blue by 

 sulphuric acid and iodine. The spore next 

 begins to enlarge and grow by cell-division, 

 one end becoming elongated into a trans- 

 parent filament like a radicle (fig. 256) ; 

 several more of these are afterwards formed 



Fig. 256. 



Spores of F. serratus in various stages of germination. 

 Magnified 100 diameters. 



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. vesiculosus 

 have been fertilized with spermatozoids of 

 F. serratus by Thuret ; but no other expe- 

 riments of hybridation were successful. 



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 

 coloured 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 la- 

 minated coat immediately surrounding the 

 spores, which when placed in sea-water 

 separate, while the coat swells and forms a 

 kind of gelatinous envelope, which appears 

 as if covered with cilia ; these pseudo-cilia 

 seem to be analogous to the similar appear- 

 ances in the gelatinous sheath of DESHI- 

 DIACEJE 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 ob- 

 servations, for the spermatozoids and the 

 actual fecundation, a power of 300. Sea- 

 water must always be used. The germina- 

 tion 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, Mar. Alg. 18, pi. 1 D ; 

 Phyc. Brit. pis. 47, 52, 158, 214 ; Greville, 

 Alg. Brit. pi. 181 ; Decaisne and Thuret, 

 Ann. Sc. Nat. 3 ser. iii. 5; Thuret, ibid. 

 xvi. 6, 4 ser. ii. 197, vii. 34 ; Sachs, Bot. 

 284 ; Bower, Jn. Mic. Soc. 1880. 



FUNA'RIA, Schreb. A genus of Funa- 

 riacese (Acrocarpous Mosses), the common 

 species of which (F. hygrometrica) is well 

 known on account of the hygroscopic cha- 

 racter of its fruit-stalk, which twists in 

 drying, and untwists again when wetted, 

 It exhibits stomata on the neck of the 

 capsule (fig. 262). 



BIBL. Wilson, Bryol. r. 268 ; Berkeley, 

 Handb. 176. 



FUNARIACE^E. A family of Funa- 

 rioidese (Acrocarpous Mosses) of loosely- 



