SACS CONTAINING CRYSTALS. 



139 



retained, while the whole series of chambers may be isolated, remaining still con- 

 nected together like a chambered fibred Hartig has called these chambered or 

 septate sacs, crystal-bearing fibres (Krystallfasern). — Similar phenomena occur also 

 in many woods, e.g. Herminiera Elaphroxylon, and on the outer surface of vascular 

 and fibrous bundles. The stegmata of Mettenius on the brown fibrous-bands of 

 Cyatheaceae (comp. p. 128) may perhaps belong more properly to this category. 



Sacs with very small and numerous crystals, as those of Solanum, Sambucus, &c., 

 usually differ but slightly in form and size from the surrounding cells. 



As regards the structure of the crystal-bearing sacs, the bundles of Raphides 

 lie at first within a protoplasmic utricle : in all, or at least in all carefully investigated 

 cases, they are enclosed, when mature, by a rather thick layer of homogeneous, 

 transparent mucilage, which is in its turn surrounded by the slightly thickened 

 cellulose wall : the mucilage reacts, in a few investigated cases '', similarly to gum 

 arabic, it swells quickly in water, and disappears (dissolves .?). It remains to be in- 

 vestigated how far this mucilage belongs originally to the membrane or to the 

 contents of the cell ; according to Frank's statements respecting the mucilaginous 

 sacs, containing a small bundle of Raphides, in the tubers of Orchis, the latter is 

 probable. The presence of the mucilage is the cause of the quick swelling of the 

 raphide-bearing sacs in water : their membrane bursts, and the Raphides escape with 

 the swelling mucilage, and scatter themselves through the water. In the elongated 

 or spindle-shaped raphide-bearing sacs, which are common, e.g. in the Aroidese, the 

 bursting and escape of the needles usually occurs, as Turpin * has thoroughly de- 

 scribed, at one or at both ends. Hansteins* raphide-containing sac- vessels (vesicular 

 vessels, ' Schlauchgefasse ') are mucilaginous raphide-bearing sacs arranged one 

 above another in long longitudinal rows. 



These series of sacs occur in large quantity in the parenchyma of many Mono- 

 cotyledons, stem and leaves of Commelinese, Palm stems, e. g. Chamsedorea : 

 Hanstein found them of large size in the foliage, stems, leaves, and bulb-scales of 

 many Amaryllidese, of the genera Amaryllis, Spreckelia, Crinum, Pancratium, 

 Eucharis, Alcestrmeria, Narcissus, Leucojum, and Galanthus. In these cases they 

 are found 1-2 layers of cells below the epidermis, and especially in the parenchyma 

 of the lower (outer) side of the leaf. In the Liliaceae they are less common : they are 

 strongly developed in the leaves of Hyacinthus orientalis, and also in Agapanthus 

 (compare Hanstein, /. c). In the foliage leaves of Scilla, Ornithogalum, Muscari, 

 there are short series, and isolated sacs, and in the scales of the bulbs of these 

 plants only isolated ones. 



The stems of Commelineae are best fitted for the investigation of the series of sacs 

 in question. In the growing internodes of these plants, both in the parenchyma of the 

 cortex and of the middle of the stem, there may be observed single longitudinal rows of 

 cells, each of which is loosely filled with a bundle of parallel raphides. The cells are at first 



1 Compare Sanio, Monatsbr. d. Berlin. Acad. 1857, p. 261; for further particulars see below, 

 Chapter XIV. 



^ Hilgers, in Pringsheim's Jahrb. VI. p. 286. 

 \ ^ Sur les biforines, Ann. Sci. Nat. 2 ser. torn. VI. p. 5. 



• Ueber ein System schlauchartiger Gefasse, etc. Monatsber. Berlin. Acad. 1859, V- 7°S-— 

 Dig Milchsaftgefasse, p. 33. 



