FORDA. 



[ 334 ] 



FRAGILARIA. 



Introd. Foram.-j Center, Ann. N. H. 1852, 

 x., 1853, xi., 1854, xiv., &c. ; Schultze, 

 Organism. Poll/thai. ; Midler's Archiv, 1856 

 (Q. J. Micr. Soc. v. 220) ; Wiegmann's 

 Archiv, 1860 (Ann. N. If. ser. 3, vii. 306) ; 

 Parker, Jones, and Brady, Ann. N. H. 2. 

 xix. j 3. in., iv., vi., viii., xi., xii., xv., xvi. ; 

 4. iv., vi., viii., ix., x. ; Q. J. Geol. Soc. xvi. 

 292, 452 j xxviii. 103 ; Phil. Trans. 1865 j 

 TV. Linn. Soc. 1864 and 1870; Monogr. 

 Crag For. (Pal. Soc.} 1866 ; lieuss, Vent. 

 Bohm. Kreid. 1845-46 ; Raiding . AbhandL 

 iv. ; Denksch. Akad. Wien, i., vii., xxiii., 

 xxv. ; 8itz. Ak. Wien, passim ; Zeitsch. dent. 

 geoL Ges. iii., vii., &c. ; Giimbel, Abhandl. 

 bai/r. Ak. x. fec. ; also the memoirs of Sol- 

 dani, R6;ner, Von Hagonow, Philippi, 

 lieuss, Czjzek, Alth, Bornemann, Egger, 

 Neugeboren, Karrer, &c. 



Since 1875 the following have added to 

 the bibliography of the subject : 



A. M. Norman, J. D. Siddall, J. II. Carter, 

 W. J. Sollas, J. F. Blake, E. Vanden Broeck, 

 Joseph Wright, H. B. Brady, A. W. Waters, 

 Ph. de la Harpe, W. K. Parker, T. R. Jones, 

 G. Stache, F. Karrer, C. W. Giimbel, J. W. 

 Dawson, 0. Schwager, M. von Hantkeu, 

 G. Steinmann, G. 0. Wallich,P. M. Duncan, 

 G. Terrigi, C. Mobius, J. Seguenza, &c. 



FOR'DA, Heyden. See APHID.*:, p. 63. 



FORFIC'ULA, Linn. F. auricularis is 

 the common earwig. 



FORMIC ACID, or acid of ants. This 

 acid occurs in ants, especially the red ant, 

 Formica rufa ; in the stinging hairs of some 

 insects, as of the procession - caterpillar 

 (Eombi/xprocessionea)', and in the poisonous 

 secretion of the stings of insects ; perhaps 

 also in the stinging organs of the Acalephae 

 and Polypes. In the higher animals it is a 

 frequent product of the oxidation of organic 

 substances, and is also found in the juice of 

 flesh, in the urine, in vomited liquids, and 

 in the blood ; also in the stinging hairs of 

 the nettle &c. 



FOSSIL INFUSORIA. The fossil 

 valves of the Diatomaceae were formerly so 

 called. See DIATOMACEAE. 



FOSSIL WOOD. This occurs in very 

 different conditions : as, for example, con- 

 verted into lignite, and the modifications 

 of coal j or with the vegetable substance 

 almost entirely removed and replaced by 

 silex, preserving all the organic forms of 

 the tissues. The mode of examining and 

 mounting COAL, &c., is given under that 

 article. Silicified woods which have been 

 completely infiltrated and solidified require 



to be cut into thin sections and polished by 

 the lapidary ; the friable kinds, where the 

 infiltration has merely filled the cavities of 

 the cells and vessels, may be split with a 

 knife and mounted in balsam. Examples 

 are given in PL 25. figs. 29-33. PI. 48. 

 fig. 32, exhibits concretions of silica imi- 

 tating structure. The stems of Palms and 

 Dicotyledonous trees are met with com- 

 pletely converted into siliceous blocks, sec- 

 tions of which exhibit all the minutiae of 

 the structure. 



FOSSOMBRO'NIA, Raddi. A genus of 

 Pellieae (Hepaticae), nearly allied in the 

 character of its vegetative structure to the 

 Jungermannieae, having large, squarish, 

 irregularly waved leaves. The stout stems 

 are procumbent, and set with purple radi- 

 cles all along the underside. The fruit- 

 stalk arises from the underside of the stem, 

 and turns back ; the perichaete is very large ; 

 and the capsule bursts irregularly into four 

 slender erose valves. F.pusilla is the Jun- 

 f/ertnanttia pusilla of the British Flora; 

 found chiefly on clay banks. 



BIBL. Hook. Brit. Jungerm. pi. 60, Brit. 

 Flor. ii. pt. 2. 117 j Endlicher, Gen. Plant. 

 suppl. i. no. 472-7. 



FOVIL'LA. The name applied to the 

 liquid granular matter filling the pollen- 

 cell and passing into the pollen-tube of 

 Flowering Plants. The minute granules, 

 which are of various but altogether indefi- 

 nite sizes, exhibit an active quivering mo- 

 tion the molecular motion, as it is called 

 which is displayed in the same way by 

 all finely-divided solid substances, living or 

 dead, and is apparently dependent on purely 

 physical causes. They appear to consist of 

 starch-grains, minute globules of oil, and 

 granules of protoplasm probably composed 

 of proteine compounds. These granules are 

 exceedingly transparent in many kinds of 

 pollen when fresh^from their refractiug- 

 power being nearly equal to that of the 

 fluid surrounding them. They may be made 

 visible by adding water. 



FRAGILA'RIA, Lyngb. A genus of 

 Diatomaceae (Cohort Fragilarieae). 



Char. Frustules (in front view) linear, 

 symmetrical, united into straight or twisted 

 ffat filaments ; valves lanceolate, oblong or 

 linear. 



Differs from Diatoma in the filaments not 

 becoming separated into zigzag chains. 

 Transverse striae only visible under oblique 

 or "stopped" illumination. 



Kutzing enumerates sixteen species, of 



