EIASTINE. 



[ 279 ] 



ELYTRA. 



all traces of the original composition vanish, 

 uniform fibres or networks alone remaining. 

 There is, however, great difference of opinion 

 among physiologists as to the development 

 of elastic tissue, some regarding it as arising 

 from fibrillation of the intercellular sub- 

 stance. 



Elastic tissue occurs in the same situations 

 in all classes of the Vertebrata as in man 

 also in some special localities, as in the 

 ligaments of the claws of the cat, the folds 

 of the wing-membrane, and the pulmonary 

 sacs of birds. In the Invertebrata, this 

 tissue appears to occur but rarely ; and it is 

 uncertain whether the elastic ligaments 

 existing in them, e.g. those of the mollusca, 

 agree anatomically and chemically with the 

 elastic tissue of the higher animals or not. 



BIBL. Kolliker, GewebeL ; Reichert, Mutt. 

 Archiv, 1856, Hft. vi. 55 ; Leydig, Hist. 27 ; 

 Frey, Histol. 1876 (very complete litera- 

 ture), 246; Beale, Simple Tissues ; Rollett, 

 Strieker's Handb. i. 59. 



ELASTINE. The proximate chemical 

 principle of which elastic tissue consists. 



EL'ATERS. This name is applied to 

 two forms of structure occurring in the 

 higher Cryptogamous Plants. The elliptical 

 spores of the Equisetacese are furnished 

 with what are called elaters, viz. four elastic 

 filaments, attached about the middle of one 

 side, which are coiled once or twice round 

 the spore before it is discharged from the 

 capsule, in the position where they were 

 originally developed; but when the spore 

 is discharged, they uncoil with elasticity, 

 causing the spore to be jerked away. They 

 appear to be produced by the outer coat of 

 the spore splitting in spiral fissures, and 

 separating in ribands from the inner coat. 

 See EQUISETACESE. 



The elaters of the Liverworts or Hepa- 

 ticae are of different nature ; they consist 

 of more or less elongated delicate mem- 

 branous tubes, which are closed cells, inside 

 which one or more elastic spiral fibres are 

 coiled up. They occur mixed with the 

 spores in the capsules of the Jungermannieae, 

 sometimes attached to the valves ; they 

 here mostly present the appearance of cy- 

 lindrical cellulose tubes, closed at the ends, 

 with a flat spiral band coiled in an open 

 spiral, adherent to the cell-membrane form- 

 ing the wall (PL 40. fig. 3d). The elaters 

 found among the spores of Marchantia poty- 

 morpha (PI. 40. figs. 36, 37) are very long, 

 and contain a double coil, the ends of the 

 two fibres coalescing into a loop at each 



extremity (PL 40. fig. 37 b) ; so that the 

 entire fibre may be compared to a piece 

 of string with its ends united, and laid out 

 so as to represent two cords, side by side, 

 which are then twisted spirally round one 

 another. In TARGIONIA the tubes are 

 sometimes branched. The development of 

 the spiral fibres is similar to that of the 

 spiral fibres of vessels. See HEPATIC^. 



Structures apparently analogous to these 

 elaters of the Hepaticaa occur in some of 

 the Myxogastrous Fungi, as in TRICHIA 

 (PL 40. fig. 390) ; while in other genera of 

 this family filamentous bodies occur, either 

 plain or obscurely marked. In Batarrea 

 also, one of the Puff-balls, a kind of elater 

 exists accompanying the spores (see TRICHO- 

 GASTRES). It has been stated by Schleiden 

 and Schacht that the elaters of these Fungi 

 are solid filaments with spiral ridges upon 

 them, or flat solid ribands twisted on their 

 longitudinal axis. This statement is at 

 variance with our observations, and is not 

 borne out by the drawings given by these 

 authors themselves. CuiTey, while also 

 contesting Schleiden's view, states that the 

 spiral line is a ridge outside a tube, a con- 

 dition of things unlike any thing else we are 

 acquainted with in vegetables. 



The elaters of Trichia require a very high 

 power for their elucidation, an eighth or 

 twelfth, with a high eyepiece, "and a good 

 light ; they may then be seen to consist of 

 tubes with spiral fibrous secondary deposits 

 upon the inside of their walls (PL 40. fig. 40). 

 See SPIRAL STRUCTURES. 



BIBL. See EQUISETACE^, MARCHANTIA, 

 TRICHIA, and SPIRAL STRUCTURES. 



ELDER. Santiucus niger, the common 

 Elder tree (Caprifoliacese, Dicotyledons), is 

 remarkable for the great development of its 

 pith ; sections of this furnish very accessible 

 and convenient illustrations of vegetable 

 parenchyma. 



ELLIPSOIDI'NA, Seguenza. An egg- 

 shaped hyaline Foraminifer, probably Gryp- 

 tostegian. The adult has three concentric 

 chambers, one within another, touching at 

 their bases and kept apart at the apices by 

 an internal column. An irregular septal 

 orifice surrounds the column as it passes 

 through the chamber-wall. E. ellipsoides 

 and its varieties only are known. From 

 the Mid-Tertiary beds of Sicily. 



BIBL. Brady, Ann. N. H. 1868, i. p. 333. 



ELYTRA. The horny anterior pair of 

 wings of the Coleoptera ; sometimes called 

 wing-covers or wing-cases, because they 



