APPENDIX. 
“ These experiments distinctly prove the origin' of Raphides, 
which appear to be compounds that become crystallised merely by 
the slow admixture of their constituents, and are probably modified 
by gummy, amylaceous, and other matters which are contained in 
the juices of the plant. Their formation does not seem confined 
to living structures or to any particular tissues or organs of a plant ; 
but the process may be carried on in any situation, as can be proved 
in the Grape vine, in which crystals can be discovered in every 
organ, and in the vascular as well as in the cellular tissue.” 
Page 44-. 
In addition to the observations of Fritzsche upon the organ- 
isation of starch, M. Payen has* lately published an elaborate 
memoir upon the same subject. He finds the granules varying 
in size between the -xVW ^ millimetre in the Potato, and the 
To%o ^ millimetre in the seed of Chenopodium Quinoa. When 
crowded within the cells that generate them they become poly- 
edral, but if floating in a thin fluid their common character is 
to be rounded. They are composed of successive thin layers, 
formed over each other, round a hilum or point of attachment to 
the wall of a cell : the matter of which they consist is of a uniform 
nature, and is formed by addition to the interior into which it 
penetrates through the hilum, the external layers being the oldest 
and toughest, and often thickened by being coated with other 
matter, such as vegetable mucus, calcareous salts, a fixed oily 
matter, and essential oil ; this additional matter is what has given 
rise to the opinion that grains of starch have a peculiar integument. 
Amylaceous matter may be found in all the organs of plants, under 
favourable circumstances, except in their nascent state ; the spon- 
gioles, very young leaf buds or flower buds, and the interior of 
the unimpregnated ovule are always destitute of starch. M. Payen 
has not found it in vessels or in intercellular passages, nor in the 
epidermis, and it is generally absent in the strata of immediately 
subjacent parenchyma. It is in the more interior parts, removed 
from the direct action of air and light, that it is principally met 
with, and especially in roots and underground forms of stem. 
{Memoire sur VAmidon : 8vo ; Paris, 1839.) 
Page 46. 
In the tubercular roots of terrestrial Ophrydeae, such as those 
which form the salep of the shops, I have shown that there 
