249 MR.C.DARWIN ON THE ACTION OF CARBONATE 
The granules precipitated through the action of carbonate of 
ammonia are never afterwards, as far as I could judge, redissolved. 
Roots still attached to living plants were immersed in solutions 
of 1 part of the carbonate to 500, to 2000, and to 4000 parts of 
water, and granular matter was deposited in the cells in the usual 
manner. The roots were then left in damp peat or in water, 
with the stems and leaves exposed to the air and light, for various 
periods between 2 and 15 days. The roots were then reexamined 
at different times, and granules were found in almost every in- 
stance in the cells. But it should be noticed that though the 
plants themselves looked healthy, the finer roots were flaccid, and 
sometimes showed evident signs of decay ; so that it was manifest 
that they had been much injured by the treatment to which 
they had been subjected, probably by their immersion in the 
solution. 
With respect to the nature of the granules, I can say but little. 
They were not dissolved by long-continued immersion in alcohol 
or in acetic acid, or by irrigation with sulphuric ether. They 
were not dissolved by a 10-per-cent. solution of common salt, 
which was tried at the suggestion of Mr. Vines, who has found 
that this solution dissolves aleurone-grains either partially or com- ` 
pletely. When sections or rootlets containing freshly deposited 
granules were left for a day or two in glycerine and water, these 
were sometimes broken up, so as to be no longer visible, and the 
cell-sap in this case acquired a brownish tint. When sections or 
thin rootlets were heated for a short time in a moderately strong 
solution of caustic potash, and afterwards left in it for a day or 
two, the granules were dissolved ; whereas the hyaline globules 
in the laticiferous ducts were not dissolved. From these several 
facts I suppose that the granules are of the nature of protein. 
After roots had been left for 2 or 3 minutes in water heated to 
a temperature of 210°-212° F., and were then placed in a strong 
solution of the carbonate of ammonia, no granular matter was 
deposited; and this seems to indicate that the action is a vital 
one. On the other hand, granules were often deposited in the 
cells, even the loose cells, of the root-cap, and it is very doubtful 
whether these could be alive. I may add that these root-cap 
cells were coloured, by a weak solution of fuchsine, of a brighter 
pink than those in other parts of the rootlets. 
Other Euphorbiaceous Plants. —The exterior cells of the roots 
of Euphorbia amygdaloides were much less acted on (Nov. 16) by 
