RAMALINA. 



[ 652 ] 



RAPHIDES. 



maceae (Fucoid Algae), containing one Bri- 

 tish species, R. verrucosa (R. deusta, Berk.), 

 forming dark-brown Lichen-like patches, 1 

 to 6" in diameter, on rocks between tide- 

 marks. The fronds are at first orbicular and 

 concentrically zoned ; they are composed of 

 densely packed, vertical, simple, jointed fila- 

 ments. The fruit is formed in wart-like 

 patches, and consists of obovate sporanges 

 attached to the bases of vertical filaments. 



BIBL. Harvey, Mar. Alg. 49. 



RAMALINA, Ach. A genus of Rama- 

 loidei (Lichenaceous Lichens), containing 

 13 British species, of shrubby habit, mostly 

 growing upon the trunks of trees, bearing 

 orbicular-peltate apothecia, nearly of the 

 same colour as the thallus. It. fraxinea, 

 fastigiata, andfarinacea are common. 



BIBL. Hook. Br. Fl. ii. pt. 1. 228; 

 Tulasne, Ann. Sc. Nat. 3. xvii. 192. 



RAMULI'NA, R. Jones. A tubular 

 branching Hyaline Foramiuifer, swollen 

 here and there into chambers, whence the 

 branches or stoloniferous tubes proceed at 

 varying angles to other such chambers. R. 

 aculeata, D'Orb., R. l&vis, and brachiata, 

 Jones, are known from the Chalk ; R. ylobu- 

 lifera, Brady, has a wide distribution in the 

 Atlantic and Pacific. 



BIBL. Rupert Jones, Proc. Belfast N. F. 

 Club, 1875, n. ser. i. 88 j Brady, Jn. Mic. 

 Sac. n. ser. xix. 272. 



RA'NA,Linn. See FROG. 



RAPH'IDES. This name was first ap- 

 plied to the minute needle-shaped crystals 

 occurring in great abundance in the tissues 

 of many plants ; but it is now generally 

 applied to all the crystalline formations 

 contained in vegetable cells. The crystals 

 are either solitary or grouped ; and some- 

 times the groups are formed on a peculiar 

 stalked matrix projecting into the cavity of 

 enlarged cells, forming the organs called 

 cystoliths. 



There are few plants of the higher classes 

 which do not contain raphides : they are 

 very abundant in the herbaceous structures 

 of the Monocotyledons generally, and espe- 

 cially those of the Aracese, Musaceae, Lilia- 

 ceae, &c. ; they also abound in the Polygo- 

 nacese, Cactaceae, Euphorbiaceae, Urticaceae, 

 &c., among the Dicotyledons. They are 

 usually found only in the interior of the 

 cavities of cells, but in some cases they occur 

 in the intercellular cavities, or in the cell- 

 walls. They may occur in almost any 

 part, but are found most extensively in the 

 steins of herbaceous plants (Monocotyledons 



in general and Cactaceae); they also occur 

 in the bark and pith of many woody plants 

 (lime, vine) ; leaves likewise frequently con- 

 tain them in vast numbers (Aracese, Mu- 

 saceae, Liliaceae, Iridaceae, Polygonaceoe) ; 

 also sepals (Orchidaceae, Geraniaceee) ; in 

 the rhubarbs, and also in Umbelliferae, they 

 occur extensively in the roots, for instance 

 in the carrot ; and they abound in autumn 

 in the base of the bulbs of the onion and 

 other Liliaceae. Raphides are often very 

 readily discovered and clearly seenin tissues, 

 by the aid of the polarizing apparatus. 



The form of the needle-shaped raphides 

 is usually that of a square prism with pyra- 

 midal ends. These ordinarily occur lying 

 parallel in bundles (fig. 614) ; another com- 

 mon form is that of rectangular or rhombic 

 prisms with oblique or pyramidal ends ; the 

 smaller of these often present themselves in 

 groups radiating from a centre (fig. 615). 

 Prisms of similar or of six-sided forms, 

 octahedra, rhombs, &c. also occur singly or 

 few together (PI. 48. fig. 28), the larger 

 ones sometimes nearly filling the cavity of 



Fig. 614. 



Fig. 615. 



Fig. 614. Parenchymatous cells of the stem of Rumex, 

 containing bundles of raphides. Magnified 400 diaim. 



Fig. 615. Parenchvmatous cells of the stem of Beta, 

 with groups of raphides (Sphaeraphides). Magnified 

 400 diams. 



the cells in which they lie. Rhombic 

 crystals of oxalate of lime occur in the 

 parenchymatous cells surrounding the vas- 

 cular bundles in the bracts of Medicago 

 trigonella ; and Gulliver has shown the 

 crystal in each cell of the testa of the elm. 

 The cells containing the bundles of acicular 

 raphides in the Araceae also contain a viscid 

 sap, which causes them to burst, through 

 endosmose, when placed in water, and dis- 



