OF AMMONIA ON THE ROOTS OF PLANTS. 241 
I should have felt little surprise at the effeet produced by the 
solution if all the eells of the same nature (for instance, if all the 
exterior cells or all the parenchyma-cells) had been equally 
affected. The strong tendency to alternation in the exterior cells 
is more especially remarkable. There is also another remarkable 
fact with respect to these latter cells, namely, that those contain- 
ing the granules do not give rise to root-hairs, as these arise exclu- 
sively from the colourless and apparently empty cells. In longi- 
tudinal sections of one root, 62 hairs were traced down to such 
colourless cells ; and I was not able to find a single one arising 
from a cell which contained granules. But I shall have hereafter 
to return to this subject. 
With respect to the rate at which the granular matter is 
deposited, if a rootlet is placed under a cover-glass and irrigated 
with a few drops of the solution, some deposition occurs before 
the slide can be transferred to the microscope and the focus 
adjusted. A thin rootlet was therefore arranged for observation, 
and a drop of the solution (7 to 1000) placed on the edge of the 
cover-glass, and in 20 seconds the cells near the tip became slightly 
clouded. Another thin rootlet was placed with the tip projecting 
beyond the cover-glâss, and the focus was adjusted to a point at 
a distance of *07 inch from the tip, on which a drop of the solu- 
tion was then placed, and the cells at the above distance became 
cloudy in 2 m. 30 sec. 
Various other solutions, beside that of carbonate of ammonia, 
caused the deposition of granules in the same cells as in the fore- 
going cases. This occurred conspicuously with a solution of 4 
parts of phosphate of ammonia to 1000 water ; but the action was 
not so rapid as with the carbonate. The same remarks are appli- 
cable to nitrate of ammonia. A solution of one part of fuchsine, 
Which contains nitrogen, to 50,000 of water distinctly acted. A 
solution of 2:5 parts of pure carbonate of soda to 1000 water 
caused, after 24 hours, the cells close to the tip to become very 
brown from being charged with fine granular matter E and higher 
up the rootlets, longitudinal rows of cells, either containing coarse 
granules or pale-brown fluid without any distinguishable granules, 
alternated with rows of colourless cells. Lastly, roots immersed 
for only one hour in a watch-glass of water, to whieh two drops of a 
l-per-cent. solution of osmie acid had been added, presented an 
extraordinary appearance ` for the exterior cells in alternate TOWS, 
some parenchy ma, and most of the endoderm-cells contained much 
almost black granular matter. 
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