APPENDIX. 
551 
microscope, when those which appear six-sided instantly appear 
four-sided, owing to the square crystal resting obliquely : this can 
be seen in the minute crystals of Squill, or in the large square 
ones of Quillaja saponaria. 
“ The rounded masses, which may be termed Conglomerate 
JRaphides in opposition to the acicular variety, seldom present 
more than the pyramid of each little crystal composing them ; but 
in a few cases, where an opportunity is afforded of examining the 
prism, it can be seen to be rectangular and terminated by a four- 
sided pyramid. 
“ Classes of Plants in which they are found. — No division of the 
vegetable kingdom seems without more or less quantities of 
these crystalline formations, which are found in a great number of 
Exogens and Endogens, and likewise in Acrogens, being visible in 
Ferns and Mosses, and, according to Unger, in the lowest of the 
Algaceae, as Nostoc Muscorum, and Conferva crystallifera. 
“ The frequency of occurrence of these bodies is such, that it 
appears that, instead of those plants containing them being excep- 
tions, those are to be considered such which have none in their 
tissues. 
It does not appear, from numerous observations, that the acicular 
and conglomerate Raphides are equally common in the several 
classes of Plants ; but that Exogens contain perhaps the one kind 
as often as the other, while Endogens undoubtedly contain most 
often the acicular variety. 
“ Situation. — The position of these bodies has been a subject of 
controversy ; Raspail asserting that they are always in the inter- 
cellular passages, whilst Turpin, Meyen, and Unger maintain that 
they are universally in the interior of the cells, which latter opinion 
is easily proved to be nearly correct by a little careful dissection 
of any plant containing them. 
“Raspail’s advice to see these bodies is to tear a piece of the 
Hyacinth stem in a drop of water placed on the stage of the mi- 
croscope, when numbers of acicular crystals will be visible (this 
method is not likely to show them in the interior of the cells) ; and 
from measuring he finds the length of the crystal longer than the 
ordinary cells of the tissue ; and therefore he decides from this, 
that they cannot be contained in the interior of the cells, while he 
overlooks the fact that the cell in which they are contained may 
be often dilated to five or six times the size of those composing the 
ordinary tissue of the plant. The square crystals in Quillaja 
saponaria appear as if loose in the plant, but they are really in a 
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