GRIFFITHSIA. 



[ 365 ] 



GRIMMIA. 



motionless filaments sometimes arise from 

 the outer surface. 



The membrane and its contents, except 

 the nucleus, are soluble in acetic acid. 



Their method of propagation, if such it 

 is, represents a form of conjugation, and 

 takes place as follows. Two individuals 

 coming into contact by corresponding por- 

 tions of the body (PL 21. fig. 34), become 

 shortened and firmly united. A transparent 

 capsule is next formed around them, which 

 encloses them in a cyst (figs. 26, 30), the 

 adjacent portions of the cell-membranes are 

 absorbed, and the substance of the two 

 bodies become intimately fused. Globules 

 or cells are then formed in the contents of 

 the cell, which subsequently assume the 

 form of Navicula, and have been called 

 pseudo-naviculee (erroneously navicellce : 

 figs. 31, 32, 33); these burst, producing 

 Amcebiform bodies, which develop into new 

 Gregarince. 



It was supposed that the pseudo-naviculae 

 were really Naviculce, and that the cysts con- 

 taining them were sporangia j but the pseu- 

 do-naviculse do not possess a coat of silex. 



In some cases it appears that the con- 

 tents of the two cells in conjugation remain 

 distinct until the pseudo-naviculse are 

 formed ; but it is not certain whether each 

 single cell in these instances has not arisen 

 from the fusion of two others. 



A very large number of species of Gre- 

 garina have been described and arranged in 

 numerous genera. 



BIBL. Dufour, Ann. Sc. Nat. 1837, vii. ; 

 Stein, Mutter's Arch. 1848 ; Ann. N. H. 

 1850, v.. and Infus. ; Frantzius, Gre.qar. 

 1846 ; Henle, Mutter's Archiv, 1835, 1845 j 

 Siebold, Naturg. d. wirbellos. Thiere, 1839 ; 

 Kolliker, Sieb. 8? Kottiker's Zeitschr. 1848 

 & 1849; Ray Lankester, Qii. Mic. Jn. 

 1863, iii. 83, and Mic. Tr. 1866, 23 (PI.) ; 

 V. Beneden (G. of lobster), Butt. I'Acad. d. 

 la Selgique, 1869 (M. M. J. 1870, 47), and 

 Ann. N. H. 1872, x. 309. 



GRIFFITH'SIA, Ag. A genus of Cera- 

 miaceae (Florideous Algae), with feathery 

 fronds 3 to 6" long, composed of delicate 

 dichotompusly-branched filaments consist- 

 ing of a single row of cells, the branchlets 

 often whorled ; colour crimson or rosy-red. 

 The fructification consists of spores, anthe- 

 ridia, and tetraspores, all produced in simi- 

 lar situations, namely at the articulations, 

 where they are surrounded by a kind of 

 involucre formed of short ramelli, to which 

 the tetraspores and antheridia are attached. 



The antheridia consist of a kind of shrubby 

 tuft of extremely minute filaments arising 

 from an axial filament which arises from a 

 ramellus of the involucre. Fig. 287 repre- 

 sents a branch terminating in an involucre 

 of whorled ramelli bearing tetraspores ; the 

 lower figure is a portion of a ramellus 



Fig. 287. 



Griffithsia sphaerica. 



Fig. 287. Fragment of a frond bearing an involucre with 

 tetraspores. Magn. 50 diams. 



Detached ramellus of the involucre, showing the at- 

 tachment of the tetraspores. Magn. 40 diams. 



showing the mode of attachment of the te- 

 traspores. In the antheridial involucres, the 

 plumose antheridial structure is attached in 

 exactly the same way. Seven British spe- 

 cies are recorded, of which one or two are 

 not uncommon. 



BIBL. Harvey, Mar. Alg. 167, pi. 23 B ; 

 Decaisne, Ann. Sc. Nat. 2 ser. xvii. p. 353, 

 pi. 16 ; Thuret, Ann. Sc. Nat. 3rd ser. xvi. 

 16, pi. 5 ; Derbes and Solier, ibid. xiv. 276, 

 pi. 36 ; Engl. Sot. pi. 1479 & 1689. 



GRIM'MIA, Ehrhart. A. genus of Or- 

 thotrichaceous Mosses, containing numerous 

 British species. 



Fig. 288. 



Grimmia. 

 Teeth of peristome. Magnified 150 diameters. 



Many of the species of Trichostomum of 



