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. Lemnacee amongst British plants are eminent for containing in their tissues 
the minute organs, to which botanists have given the name of Raphides. This word — 
is derived from jagic, 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 saline 
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 published 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 in others. Ina 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 Flora.’ And having thus, as well as by repeated independeni 
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 arbitrary or technical distinction, but as a truly regular and 
natural difference.” 
Raphides can be easily detected with a compound microscope haying a quarter of ¢ 
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 ce 
containing the raphides are usually larger than the surrounding ones which do no 
contain them. The raphides are not attached to each other, but lie loosely together, 
and they are frequently observed to escape from the cell under gentle pressure. The 
vary in size in the same plant, and more indifferent species and orders. According 
to Mr. Gulliver’s measurements, they vary from the 3, of an inch in length to 
yster 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 fe v { 
‘ 
crystals are found together. Such crystals are found in the species of the genus 
Tris. Sometimes several of these crystals adhere together by their base, and form a 
more or less rounded body, and to these the name sphwraphides has been ne 
Such crystals have been found in the Elm and Cranesbill, and have had the na 4 
cysto-lithes and crystal glands applied to them. 
Raphides are composed of various materials. The needle-shaped prisms consi 
of phosphate of lime, whilst the crystal prisms are composed of oxalate of lime ¢ 
magnesia; the sphrraphides seem principally composed of oxalate of lime. 
