EECEEATIVE SCIENCE. 



243 



Tliis resemblance at once suggested the 

 name, from tlie Greek word raphis, a needle ; 



Fio. 1.— Acicular Eaphides. A, from hyacinth ; B, 

 in tissue of squill bulb ; C, one of the longest from 

 squUl ; D, from orris-root. 



it is now applied, with an extended meaning, 

 to all crystalline concretions found in plants. 

 As the hyacinth is not to be procured during 

 a considerable portion of the year, the bulb 

 of the medicinal squUl {Scilla maritima), 

 which can at any time be purchased, may 

 be had recourse to. A moderately thin layer 

 should be sliced off with a razor, parallel to 

 the surface; with a few minutes' immersion 

 in water the cells become so transparent as 

 almost to lose their contours, and then the 

 raphides may be distinctly seen in groups, 

 looking like packets of fine needles, assorted 

 in sizes Fig. 1, b). Round each packet may 

 generally be observed its wrapper, which 

 might be compared to a very delicate bladder 

 — in technical langxiage, a wall of protoplastic 

 material. When thus seen lying together, the 

 difference in their size is one of the first points 

 to catch the eye. To express in a familiar 

 manner their relative length, it may be said 

 that, of the smallest, if set end to end, a 

 thousand would be required to bridge over 

 the space of an inch, whilst of the largest 

 about twenty-two only would be needed to 

 cover the same. 



The situation of raphides has formed a 



long-standing subject of controversy, some 

 asserting that they were always situated in 

 cells, whilst others maintained that they 

 occurred in the intercellular passages. The 

 latter are spaces left between the rounded 

 cells of lax tissue. A good example of them 

 is found in the 

 carrot-root, by 

 making a very 

 thin section af- 

 ter it has become 

 somewhat dry 

 through beiag 

 left about for a 

 few days (Fig. 

 2). The rea- 

 soning that the 

 raphides were 

 longer than, and 

 therefore could 

 not be contained 

 in, the cells of 

 hyacinth, is very 

 loose, and as it 

 happens incor- 

 rect, since the 

 cells in which 

 they are found 

 are much larger 

 than ordinary. 

 But it is always desirable, when we can do 

 it, to look at things as they grow, without 

 any possibility of disturbance from cutting 

 or tearing. In the walls of the anther of 

 hyacinth they may be seen in situ, but they 

 are most readily observed in the petals of 

 Oenothera, Clarkia, or epilobium. Take 

 one of these, gently lay it on a slide with 

 water and a covering glass ; it is very deli- 

 cate, rapidly becomes exceedingly hyaline, 

 and then, standing sharply out from the rest 

 of the structures, will be seen long, thick- 

 walled cells, containing, though seldom filled 

 with raphides. Large cells of a similar kind 

 are found finely developed in the leaves of 

 the banana, Musa sjp. If thin sections of 



Fig. 2. — Intercellular Passages 

 in Tissue of Eoot of Carrot ; 

 some are black from con- 

 tained air. 



