OF AMMONIA ON THE ROOTS OF PLANTS. 255 
coloured granules, unlike those in the same cells after immersion. 
Thick and thin roots were left for 22 hours in a solution of 7 to 
1000, and the cells forming the exterior layer were filled over con- 
siderable spaces with green granules, while over other spaces they 
were empty. The granular and empty cells did not form regular 
alternate rows, as occurs in so many other plants; yet,as we shall 
presently see, there is occasionally some degree of alternation. 
The exterior cells with the green granules were so numerous in 
certain cases, that roots which had been pale brown before immer- 
sion were afterwards distinctly green. The green granules some- 
times became aggregated into spherical, or oval, or elongated 
masses having a sinuous outline; and some of these are siown 
within the root-hairs in fig. 2. Many of the cells of the paren- 
chyma, either standing separately or two or three in a row (as 
shown in fig. 1), contain similar green, or sometimes brownish, 
granules. Almost all the narrow elongated cells of the endoderm 
(4, fig. 1) likewise contain these granules, with merely here and 
there an empty cell. Although both kinds of cells often appear 
as if gorged with the granules, yet these really form only a layer 
adhering to the inside of the protoplasmic utricle, as could be seen 
when cells had been cut through. With some thick fleshy roots, 
after an immersion for 42 hours (and thick roots require a long 
immersion for the full effect to be produced) the green granules 
in the parenchyma-cells had become completely confluent, and 
now formed spheres of transparent green matter of considerable 
size. 
The granules are not dissolved, nor is their colour discharged 
by sulphuric ether. Acetic acid instantly changes the green into 
a dull orange tint. The granules are not dissolved by alcohol. 
Their precipitation by the ammonia solution seems to depend on 
the life of the cell; for some transverse sections were examined 
and found colourless, as well as destitute of granules. They were 
then irrigated with a solution of 7 to 1000, and reexamined after 
22 hours; and only a very few cells in two out of the five sections 
showed any trace of colour, which, oddly enough, was blue instead 
of green. The few coloured cells occurred exclusively in the 
thickest parts of the sections, where the central ones would ob- 
viously have had the best chance of keeping alive for some time. 
In these coloured cells a little very fine granular matter could be 
distinguished. 
On most of the roots root-hairs were extremely numerous, 
LINN. JOURN.— BOTANY, VOL. XIX. * 
