18 ENGLISH BOTANY. 



to the avidity with which ducks devour the tender leaves of which they are composed. 

 It is, however, to the observer, microscope in hand, that they afford the greatest 

 interest. Lemnacece amongst British plants arc eminent for containing in their tissues 

 the minute organs, to which botanists have given the name of RnjMdes. This word 

 is derived from jjafig, the Greek for needle, in allusion to the needle-like form which 

 many of these bodies assume. They are, in fact, the minute crystals of various salino 

 matters, which are taken up into the tissues of plants, and whilst forming a part of the 

 bulk of the living plant, nevertheless obey the lower laws of crystallisation. At one 

 time it was thought that these bodies were accidental, and little attention was paid to 

 their presence or absence in plants. In a paper pubUshed in the " Quarterly Journal 

 of Microscopical Science," Dr. Lankester called attention to the constant occurrence 

 of raphides in certain orders of plants, and since then Professor Gulliver has published 

 a series of exhaustive observations on the subject, in which he shows that not only 

 are raphides constantly present in some orders and species of plants, but that they are 

 as persistently absent iu others. In a paper on this subject in the " Popular Science 

 Review," vol. iv. he says, " If we examine the cells in the leaves, in fruits which are 

 modifications of leaves, and the stem, fruit, root, and other organs of some of the 

 flowering plants most commonly seen in our walks — say, a willow herb or bedstraw, 

 a loosestrife or honeysuckle — we shall get remarkable results. Indeed, so plain and 

 simple, so significant and beautiful will they prove, that our first feeling may well be 

 one of surprise that such characters have not been long since discovered and usefully 

 realised in descriptive or systematic botany. While we find raphides constantly 

 abounding in the former two plants, in the latter two we shall as constantly find 

 raphides wanting, and this in examples now purposely chosen from neighbouring 

 orders of the ' British Floi-a.' And having thus, as well as by repeated independent 

 trials, found the constancy and truth of this character, how can we avoid the convic- 

 tion that to the first two plants Nature has assigned, as an essential and intrinsic 

 function, by a structure of organic cells, the office of raphis-bearing, while to the last 

 plants she has not appointed that same office or structure ? And so this will appear 

 to us not merely as an arbitraiy or technical distinction, but as a truly regular and 

 natural difference." 



Raphides can be easily detected with a compound microscope having a quarter of an 

 inch objective. They are usually transparent and colourless, and of a needle shape, 

 occurring in bundles of from fifteen to twenty in number. They are generally found 

 lying across the oval cells of plants, and frequently project beyond the cell. The cells 

 containing the raphides are usually larger than the surrounding ones which do not 

 contain them. The raphides arc not attached to each other, but He loosely together, 

 and they arc frequently observed to escape from the cell under gentle pressure. They 

 vary in size in the same plant, and more in different species and orders. According 

 to Mr. Gulliver's measurements, they vary from the 4s of an inch in length to the 

 l^l^f, of an inch in breadth. Sometimes raphides present themselves in the form 

 of a prism. They are then not so long in proportion to their breadth, and only a few 

 crystals are found together. Such crystals are found in the species of the genus 

 Iris. Sometimes several of these crystals adhere together by their base, and form a 

 more or less ro\mded body, and to these the name sphteraphides has been applied. 

 Such crystals have been found in the Elm and Cranesbill, and have had the name 

 cysto-lithes and crystal glands appUed to them. 



Raphides are composed of various materials. The needle-shaped prisms consist 

 of phosphate of lime, whilst the crystal prisms are composed of oxalate of lime and 

 magnesia; the spli£craphides seem principally composed of oxalate of lime. Other 



