252 MR. C. DARWIN ON THE ACTION OF CARBONATE 
grains They were then irrigated with a solution of 7 to 1000; 
and in from 10 to 15 minutes they became very opaque, especially 
near tbeir tips. After being left a little time longer in the solu- 
tion, longitudinal sections were made. The cells forming the 
exterior layer contained no solid matter, but the walls had become 
brown. There was much brown, finely granular matter in many 
of the parenchyma-cells at different depths from the surface; and 
these formed interrupted longitudinal rows, which alternated in 
the same zone with rows of empty colourless cells. Almost all 
the endoderm-cells likewise contained granules. In the paren- 
chyma the cells which included much granular matter contained 
no starch-grains; while those abounding with starch-grains con- 
tained only a few or no granules. The fact was best seen after 
the sections had been irrigated with a solution of iodine; and they 
then presented a very remarkable appearance, considering how 
homogeneous they had been before being treated with the am- 
monia and iodine; for the fine granular matter was rendered 
still browner and the starch-grains of a beautiful blue. These 
roots were left for a week in diluted aleohol, and the granules 
were not dissolved. 
Not a single root-hair could be found on these roots. A rooted 
stolon was therefore dug up and potted on Dee. 19th; it was then 
forced forwards in the hot-house, and afterwards kept very dry. 
When examined on Jan. 3rd the roots were found clothed with 
innumerable root-hairs ; and they were then left for 23 hours in 
the solution of 7 to 1000. — Sectiorfs of the thicker roots presented 
exactly the same appearances as described above ; and the exterior 
cells, from which the root-hairs arose, were destitute of granules. 
The thinner roots differed somewhat in appearance, as the paren- 
chyma-cells did not contain any fine granules, but in their places 
small, spherical, or oval, or irregularly-shaped masses or filaments 
of brown translucent matter, resembling a highly viscid fluid. 
There were also in these cells other still smaller colourless spheres. 
The cells, however, close to the tip of the root were filled with 
brown granular matter. 
Solanum (capsicastrum ? var. Empress). — Roots, after an immer- 
sion of 203 hours in a solution of 4 to 1000, were split longitu- 
dinally and examined, but with no great care. The exterior cells 
did not appear to have been affected ; but some of the parenchyma- 
cells close beneath the exterior cells contained minute aggregated 
masses of brown, opaque, or sometimes hyaline granules. More- 
