OF AMMONTA ON THE ROOTS OF PLANTS. 243 
a solution of carbonate of ammonia than those of Z. Peplus. 
Here and there two and three cells in a row contained brownish 
granules, and these abounded in the elongated endoderm-cells. 
Nearly the same remarks are applicable to E. myrsinites, though 
in most specimens the cells with granules were stil rarer. The 
roots of two fleshy species, Z. rhipsaloides and ornithopus, did not 
appear to be at all affected by the solution. 
Turning now to other Euphorbiaceous genera, the roots of 
Poinsettia pulcherrima, Manihot Glaziovi, Croton oblongifolium, 
and Hevea Spruciana were not affected. Nor were those of Mer- 
curialis perennis, as far as the exterior cells are concerned; 
but here and there a single cell in the parenchyma became 
blue; but these cells were not carefully examined *. Judging 
from the cases presently to be given, they probably contained 
granules which had been precipitated by the ammonia solution. 
On the other hand, the roots of Phyllanthus compressus were 
conspicuously acted on by an immersion of 21 hours in a solu- 
tion of 4 parts of the carbonate to 1000 of water, though in a 
somewhat different manner from those of Euphorbia Peplus. In 
parts the exterior cells in many adjoining longitudinal rows con- 
tained brownish granules; while in other parts at no great dis- 
tance many adjoining rows were colourless and empty—that is, 
contained no solid matter. For instance, in one place 13 longi- 
tudinal rows with granules ran alongside one another, then came 
a single row of empty cells, and then at least 9 rows with gra- 
nules. In another place there were 13 adjoining rows of cells 
allempty. When one of these rows was followed up or down 
the root for some distance, it changed its character, either 
becoming or ceasing to be granular, and then resuming its 
former character. Close to the tips of the roots all the longitu- 
* The rhizomes and buried parts of the stems of this plant are white ; but 
after immersion for a day in the ammonia solution they became in parts either 
pale or rich blue. This change of colour occasionally occurred in parts exposed 
to the air which had not been subjected to the solution. As a similar change 
occurs in certain cellsin the roots of various plants after their immersion in the 
solution, I asked Mr. Sorby to be so kind as to examine the rhizomes and under- 
ground stems of the Mercurialis. He informs me that he does not understand 
the change of colour ; but he was unable to spare time for a full examination. 
He found that when the rhizomes and stems were boiled in alcohol, they yielded 
matter which was soluble in water, and which appeared to pass so rapidly into 
a brown substance with curious shades of green, that the real change was hidden. 
On the whole, the appearances differed a good deal from those observed by him 
in the case of blue flowers. 
