OF AMMONTA ON THE ROOTS OF PLANTS. 245 
The foregoing observations on the Euphorbiacex led me to ex- 
periment on the roots of some other plants belonging to various 
families. At one time I erroneously imagined that there was 
some relation between the deposition of granules in certain cells 
and the presence of laticiferous ducts, and consequently an undue 
number of plants with milky juice were selected for observation. 
A solution of carbonate of ammonia produced no obvious effect 
on the roots of a small majority of the plants which were tried ; 
but on several a slight, and on others a marked, effect was pro- 
duced. I should state that when the exterior appearance of a root 
did not indicate any action, sections were rarely made ; so that the 
interior cells were not examined. No obvious effect was produced 
with the following plants :— Argemone grandiflora, Brassica ole- 
racea, Vicia sativa, "Trifolium repens, Vinca rosea, Hoya campanu- 
lata, Stapelia hamata, Schubertia graveolens, Carica Papaya, Opuntia 
boliviensis, Cucurbita ovifera, a Begonia, Beta vulgaris, Taxus 
baccata, Cycas pectinata, Phalaris canariensis, a common pasture- 
grass, Lemna, and two species of Allium. It may perhaps be 
worth notice that the radicles, but not the hypocotyls, of seed- 
lings of Beta vulgaris were completely killed by an immersion for 
20 hours in solutions of either 4 or of only 2 parts of the carbo- 
nate to 1000 of water; and this occurred with no other plant 
which was tried. 
With the following plants the solution produced some slight 
effect. The roots of a fern, Nephrodium molle, were immersed for 
20 hours in a solution of 4 to 1000; and this caused the deposi- 
tion of some brown granular matter in the cells near their tips ; 
and more or less confluent globules could be seen in the under- 
lying parenchyma-cells. So it was with an unnamed greenhouse 
species of fern; and in this case the almost loose cells of the root- 
cap contained brown granules. The roots of a Ranunculus 
(R. acris ?) similarly treated exhibited near their tips brown gra- 
nular matter. The tips also of the roots of Dipsacus sylvestris 
became, under similar treatment, almost black; and higher up 
the roots, here and there a single parenchyma-cell was coloured 
pale blue. This occurred in one instance when a rootlet was 
looked at 35 minutes after irrigation with the solution. Several 
roots of Apium graveolens were left for 20 and 24 hours in solu- 
tions of 4 and 7 to 1000; and in some cases brownish granules, 
more or less aggregated together, were deposited in some of the 
exterior cells, and a few of the deeper cells in the parenchyma 
