OF AMMONIA ON THE ROOTS OF PLANTS. 257 
however, in other cells were plainly visible ; and, lastly, a few of 
these eells included spherical or oval masses of the same nature as 
those just mentioned in the exterior cells. Most or all of the 
endoderm-cells either contained a homogeneous brown fluid, or they 
appeared, from including excessively fine granules, like a mezzo- 
tinto engraving. Inno case were any of the cells coloured green. 
Some roots were immersed for from 20 to 44 hours in a solu- 
tion of carbonate of potash of 7 to 1000: and these were affected 
in nearly the same manner as those in the soda solution. In the 
exterior cells, however, more granules were deposited ; and these 
were oftener aggregated together, forming transparent orange- 
coloured spheres. The cells containing the granules or spheres 
were of a brown colour, and were arranged in longitudinal rows 
which alternated with rows of colourless cells. There were 
fewer granules in the parenchyma-cells than in the roots which 
had been subjected to the soda solution; and there were none in 
the endoderm-cells, even in roots which had been left immersed 
for 44 hours. A solution of phosphate of ammonia (4 to 1000) 
produced no effect on the roots after 43 hours' immersion. 
Concluding Remarks.—The most remarkable conclusion whieh 
follows from the foregoing observations is that, in the roots of 
various plants, cells appearing quite similar and of the same 
homologous nature yet differ greatly in their contents, as shown 
_ by the action on them of certain solutions. Thus, of the exte- 
rior cells, one, two, or more adjacent longitudinal rows are often 
affected ; and these alternate with rows in which no effect has 
been produced. Hence such roots present a longitudinally 
striped appearance. Single cells in the parenchyma, or occasion- 
ally two or three in a row, are in like manner affected ; and so it 
is with the endoderm-cells, though it is rare when all are affected. 
The difference in aspect between sections of roots before and 
after their immersion in a proper solution is sometimes extra- 
ordinarily great. Of all the solutions tried, that of carbonate of 
ammonia acts most quickly, indeed almost instantaneously ; and in 
all cases the action travels up the root from cell to cell with re- 
markable rapidity. With Euphorbia Peplus a solution of 1 part 
of the carbonate to 10,000 of water acted, though not very 
quickly. : 
When the action is very slight, the fluid contents of the cells 
are merely rendered pale brown. Nevertheless, judging from the 
gradations which could be observed, the brown tint is probably 
