246 



EECREATIVE SCIENCE. 



ment in tlie acicular form were not success- 

 fully imitated. 



Their uses are unknown. In tlie economy 

 of tlie plants possessing them, they serve no 

 apparent purpose, and may even be regarded 

 rather as noxious products. It may be sug- 

 gested that in some plants, at least, they 

 serve the after-purpose of rendering the 

 tissues brittle, and so facilitate decomposi- 

 tion. Their numbers are occasionally enor- 

 mous — in rhubarb-root, out of every 100 

 grains of the best Turkey, 35 are these 

 useless crystals, in East Indian 25, in Eng- 

 lish, such as is sold in the streets by men 

 dressed up like Turks, 10 — buyers of this 

 drug judge of its quality by its grittiness. 

 This has been considered a puzzle, but the 

 explanation is simple : the same ardent suns 

 that increase the quantity and power of the 

 resinous purgative, pari passu, increase the 

 amount of saline ingredients. A lime-tree 

 having decayed, was cut down, the bark 

 came off in large pieces, and as it fell, 

 showers of dust came away, composed of 

 the long, flattened prisms peculiar to it. 

 Some of the cacti seem to become almost 

 wholly composed of raphides. The two re- 

 markable specimens of Cereus senilis, sent a 

 few years ago from South America to Kew, 

 will be in the recollection of all ; these were 

 supposed to be about one thousand years old, 

 were so brittle as to fracture with a touch, 

 and required packing in cotton wool, with 

 all the care of the finest jewellery. A lively 

 description, with sketches, was given in the 

 Illustrated London News of the day. 



Besides the higher plants, some of the 

 ferns and mosses are stated to possess ra- 

 phides, together with plants even lower in 

 the scale. By favour of Mr. Shirley Hib- 

 berd, the opportunity has been afforded of 

 examining a confervoid growth, detached by 

 the action of frost from an aquarium. It 

 was composed, iirincipally, of the mucous 

 investment- of oscillatoria, with numerous 

 compound crystals (Fig. 5) that dissolved 



rapidly in dilute muriatic acid, with much 

 effervescence, leaving an organic residue. 



Mr. F. Currey has lately met with acicular 

 raphides in one of the lower fungi {Phlebia 

 mesenterica), and has ascertained that crys- 

 tals were formed rapidly and in immense 

 numbers in a myriophillum, as the plant 

 decayed. These were of the stellate form, 

 and occurred in the intercellular passages. A 

 good figure and description of them are given 

 in the Phytologist for April, 1859. 



Most raphides may be well preserved in 



Fig. 5. — Crj-stalline Masses from Mucous Stratum of 

 Oscillatoria. G, gelatinous substance left after 

 dissolution of one by acid. 



glycerine or Canada balsam, if it be not an 

 object to show the tissues in which they 

 have their seat. When mounted on a dead 

 black ground, as opaque objects, dry, the 

 stellate forms are especially beautiful. To 

 obtain them clean for this purpose, the en- 

 veloping tissues must be entirely destroyed 

 by maceration, the crystals repeatedly 

 washed, and afterwards dried. 



Some crystalline masses have been de- 

 scribed as occurring in the stem of a fossil 

 palm, which appeared to be raphides turned 

 to stone ! 



Polarized light may be used with advan- 

 tage in the examination of raphides. The 

 play of the prismatic colours thus developed, 

 is often, very beautiful. 



Tttfpen West. 



