ACTION OF CARBONATE OF AMMONIA ON ROOTS OF PLANTS. 239 
The Action of Carbonate of Amma on the Roots of certain 
Plants. By Contre DARWIN, LL.D., F.R.S. 
[Read March 16, 1882.] 
Many years ago I observed the fact that when the roots of 
Euphorbia Peplus were placed in a solution of carbonate of am- 
monia a cloud of fine granules was deposited in less than a 
minute, and was seen travelling from the tip up the root from 
cell to cell *, The subject seemed to me worthy of further in- 
vestigation. Plants of the same Euphorbia were therefore dug 
up together with a ball of earth, and having been left for a short 
time in water, the roots were washed clean. Some of the finer 
transparent rootlets were then examined, and sections were made 
of the thicker roots, generally by my son Francis, who has aided 
me in many ways. All the cells were found to be colourless and 
destitute of any solid matter, the laticiferous ducts being here 
excluded from consideration. These roots, after being left for a 
few minutes or for several hours in solutions of different strengths, 
viz. from 1 to 7 parts of the carbonate to 1000 of water, presented 
à wonderfully changed appearance. A solution of only 1 part to 
10,000 of water sufficed in the course of 24 hours to produce the 
same result. In well-developed cases the longitudinal rows of cells 
close to the tip of the root, with the exception of those forming 
the extreme apex, were filled with brown granular matter, and 
were thus rendered opaque. o Long-continued immersion in water 
Produced no such effect. The granular masses were square in 
outline, like the cells in which they were contained; but they 
often became rounded after a day or two; and this was apparently 
due to the contraction of the protoplasmic utricle. Above the 
dark-brown cells, which form a transverse zone close to the tip, 
and which apparently corresponds with the zone of quickest 
&rowth, the roots, as seen under a high power, are longitudinally 
Striped with darker and lighter brown. The darker tint is due 
to the presence of innumerable rounded granules of brownish 
matter; and the cells containing them are arranged in longitu- 
dinal rows, while other longitudinal rows are destitute of granules. 
In a few instances the rows differed slightly in tint, and yet no 
* “İnsectivorous Plants,’ 1875, p. 64. The subject was at that time, 22 years 
ago, only casually investigated ; and I believe that I erred greatly about Lemna, 
unless, indeed, some different species was then observed, or that the season of 
the year makes a great difference in the behaviour of the roots, which is not 
Probable, 
LINN. JOURN.—BOTANY, VOL. XIX. x 
