24 QuEKETT on the Raphides of Cactus enneagonus. 
acid, but I was much astonished to find that in many cases a 
basis or cast of the entire mass was left behind after the action 
of the acid had ceased ; and in most instances I could tell pre- 
cisely not only the spot where the crystals had been, but also 
form some general idea of the shape of the mass, and instead 
of their being, as I first imagined, a mass of crystals only, 
I found that there was some organic matter or basis connected 
with them. 
When one of these raphides is crushed between two plates 
of glass, the outer crystals are readily detached ; some of these 
are represented by fig. 6 : the part composing the nucleus is 
much the hardest, and exhibits a radiated and concentric 
laminated deposit, like the masses of carbonate of lime found 
in the urine of the horse. If portions of the cellular tissue of 
the cactus be examined, some cells will occasionally be found 
in which a more or less spherical mass, as shown in fig. 5, 
occurs in the centre of each : these masses correspond in every 
respect with the nuclei of the larger raphides ; it would there- 
fore appear that in the early stages of development of these 
raphides the nucleus consisted of one of these spherical bodies, 
and the crystals on the exterior were formed subsequently. It 
may also happen that the bases of some of the crystals in 
process of time coalesce to form laminae, a condition not 
unlike that occurring in shell, as has been so well described by 
Dr. Carpenter, or rather like that which takes place in the 
formation of most of the laminated kinds of urinary calculi. 
My object in bringing the subject before the Society at this 
time is to ask those of our members who are chemists, and 
would be willing to look into the matter, if they could deter- 
mine the nature of the residuum or basis left after the destruc- 
tion of the earthy ingredient by means of the acid. They will 
find, as I shall presently have the opportunity of showing you, 
that there is something peculiar in the dissolution of the 
crystals — they are all, more or less, granular, as if the organic 
matter were not confined to the investing membrane, but inti- 
mately mixed up or incorporated with every atom of the lime. 
I have this day examined some sections of the Soap wood of 
China, in which stellate masses of crystals are very abundant. 
If these be acted on by dilute hydrochloric acid, the earthy 
constituent will disappear, but a cast of the original mass will 
be preserved in what may be termed organic matter. This 
point, however, is the one which requires to be carefully ex- 
amined by persons more skilled than myself in the science of 
organic chemistry. 
As far as my observations have hitherto gone, it would 
appear to be a rule that we rarely, if ever, find inorganic 
