GOMPHONEMA. 



[ 294 ] 



GONATORRHODON. 



grows up between the inner of the first two 

 and the nucleus, and after fertilization pro- 

 jects out of the exostome as a tubular pro- 

 cess with a fimbriated extremity. 



BIBL. Lindley, Vegetable Kingdom, art. 

 GnetacecB. 



GOMPHONEMA, Ag. A genus of Dia- 

 tomacese. 



Char. Frustules mostly single or binate, 

 attached by a filiform stipes, wedge-shaped 

 in front view ; valves with a median line and 

 a nodule at the centre and at each end, and 

 striated with transverse or slightly radiating 

 lines resolvable into dots. Aquatic and 

 fossil. 



Conjugation has been observed in several 

 species. 



Kiitzing describes thirty-eight species, 

 Smith admits twelve as British. The form 

 of the frustule is subject to great variety, 

 and the specific characters are probably of 

 little value. 



The most common species are : 



G. acuminatum (PL 12. fig. 34, a, b, c). 

 Frustules in front view simply cuneate, or 

 inflated in the middle ; valves attenuated at 

 the base, ventricose in the middle, beyond 

 which they are again expanded; ends acumi- 

 nate, or truncate with an acuminate pro- 

 longation; striae distinct; length of frustules 

 1-360". (San Fiore deposit.) 



G. geminatum. Valves ventricose in the 

 middle, constricted and rotundo-truncate 

 towards each end; striae distinct; stalks 

 long, thick, densely interwoven; length of 

 frustules 1-216 to 1-180". 



G. olivaceum. Densely crowded, forming 

 a mucous mass; frustules broadly cuneate 

 (fr. v.) ; valves obovato-lanceolate ; striae 

 distinct; length of frustules 1-1020". 



G. curvatum. Frustules curved; valves 

 obovato-lanceolate; striae faint; length 

 1-720". 



BIBL. Ehr. In/us, p. 215; Kiitzing, Ba- 

 cill. p. 84, and Sp. Alg. p. 63 ; Smith, Brit. 

 Diatom, p. 77; Ralfs, Ann. Nat. Hist. 1843. 

 xvi. p. 459. 



GONIDIUM. The name applied to cells 

 which in the Thallophytes perform an office 

 analogous to that of the GEMMAE of the 

 higher Cryptogams, and the separating bud- 

 structures, such as bulbils, stolons, &c. of 

 the Flowering Plants ; being cells developed 

 from the vegetative tissues, ultimately thrown 

 off, and capable of propagating the indivi- 

 dual. The gonidia of the Lichens are glo- 

 bular cells with green contents developed in 

 the central layers of the thallus, afterwards 



set free by the destruction of the cortical 

 layer ; they appear capable of multiplication 

 by subdivision before growing out into the 

 filaments which form the foundation of the 

 new thallus (see LICHENS). The gonidia 

 of the Fungi are usually termed CONIDIA 

 (see that article, and FUNGI). The gonidia 

 of the Algae are best known in the CONFER- 

 VOIDS, where they are formed from the cell- 

 contents, and generally present themselves 

 ciliated, as ZOOSPORES. The tetraspores of 

 the Florideae are probably the homologues of 

 gonidia. 



GONATOBOTRYS, Corda. A genus of 

 Mucedines (Hyphomycetous Fungi), the fer- 

 tile filaments of which present at intervals 

 swollen articulations, on which are attached 

 simple ovate spores (figs. 288, 289). 



BIBL. Corda, 



Fig. 288. 



Fig. 289. 



Gonatobotrys simplex. 



Fig. 288. A fertile filament. Magn. 100 diams. 

 Fig. 289. A sporiferous joint, with most of the spores 

 removed. Magn. 600 diams. 



GONATORRHO- Fig. 290. 



DON, Corda. A 

 genus of Mucedines 

 ( Hyphomycetous 

 Fungi), the fertile 

 filaments of which 

 have at intervals 

 swollen articulations, 

 whence arise monili- 

 form chains of spores 

 (fig. 290). 



BIBL. Corda, 

 Prachtfl. Europ. 

 ScMmmelb. pi. 3. 



Gonatorrhodon speciosum. 



Fertile filaments with swollen joints bearing chains of 

 spores. Magn. 100 diams. 



