234 
examine, under an achromatic object-glass of half an inch 
focal length, fine longitudinal sections of the plant-tissue, or 
fragments of it mashed by the point of a penknife in a drop 
of water, on the object-plate. Deeper magnifying powers, 
of course, will be needful for further research. Sphaerapliides 
are often best seen in these transverse slices of the stem and 
leaves ; and the sphseraphid tissue in delicate films either 
cut or torn off lengthwise. 
And now we may proceed to explanations in due order of 
the remaining questions, and for this purpose suitable ex- 
amples will he selected from the most familiar plants of our 
own fields and gardens, and from common officinal things. 
More extensive and particular details may he found, espe- 
cially as regards measurements, composition, etymologies, 
and the distribution of raphides in the Flora of Britain and 
of the world, in my papers published elsewhere . 1 
1. Raphides. — These are slender needle-like crystals, 
with rounded, smooth shafts, vanishing at each end to a 
point, from about ten to fifty or more lying parallel together so 
as to form a bundle which partially fills a cell or intercellular 
space. When undisturbed, this bundle lies along its cell, 
but the raphides are often so easily displaced by slight 
pressure on the object-plate, that either all or part of them 
cross the cell in various directions, sometimes gravitating to 
one of its ends, and occasionally escaping quickly from one 
or both of them. In this last case they have been described 
as “ biforines ” by the continental writers. Thus, though 
the raphides lie close together in each bundle, their connection 
with each other is really as loose as that between a packet 
of sewing-needles, and, accordingly, when these crystals are 
first shown to a novice, their likeness to a lot of needles is 
sure to be noticed. The raphis-cell is commonly very 
distinct, often oval and tumid ; it contains a lot of viscid or 
1 “On Raphides,” &c., various numbers of ‘Annals of Natural History,’ 
1861-1865 ; ‘ Seemann’s Journal of Botany,’ March, 1S64 ; ‘Quart. 
Journal Micros. Science,’ January, 1864; “Raphides as Natural Cha- 
racters,” in the ‘ British Flora,’ ibid., January, 1866; and in the “Flora of 
the World, with Epitome of my former Observations,” ‘Popular Science 
Review,’ October, 1865 ; “Cells and Raphides of Duckweeds and Exra- 
phidian Character of Wolffia,” with figures, ‘Seemann’s Journ. Bot.,’ Dec., 
1866, and January, 1869 ; “Pith-Cells of Rushes,” ‘Ann. Nat. Hist.,’ 
plate vii, figs. 13 and 14, December, 1863 ; “ Vegetable Fibrin and Latex,” 
ibid., Marcli, 1862 ; “ Tissue-Cells and Spores of Hymenophylleae,” with 
figures,?'^., August and October, 1863, and ‘Seemann’s Journ. Bot,’ 
October, 1863; “Pollen-Grains,” ‘Annals Nat. Hist.,’ July, 1865; “See- 
mann’s Journ. Bot.,’ with figures, September, 1866; ‘Popular Science Re- 
view,’ July, 1868. 
