OF AMMONIA ON THE ROOTS OF PLANTS. 249 
besides the granules, oval and occasionally spherical masses of 
transparent, almost colourless matter, which apparently did not 
change their shapes. The cells round the central vascular bundle 
included similarly shaped masses, but of a yellowish-brown colour. 
These roots and others were left for 24 hours in the solution 
of 7 to 1000, and their tips were now blackened. Some of the 
exterior cells, more especially those of the thicker roots, were 
filled with orange instead of brown granules ; while other cells 
contained oval, spherical, or oddly shaped masses of orange, 
instead of almost colourless or pale-brown translucent matter. 
Some of these masses consisted of an aggregation of small, par- 
tially confluent spheres of different tints of orange. In trans- 
verse sections it could be seen that the two exterior layers of cells 
and those surrounding the vascular bundle contained the above- 
described masses, while the more central parenchyma-cells 
abounded with grains of starch. A solution of 4 parts of the 
carbonate to 1000 of water sufficed to produce similar effects. 
The root-hairs, after immersion in the solution, were not so 
transparent as is commonly the case, from including very fine 
granular matter, and from their shrunken protoplasmic lining 
being of a yellowish colour. The roots themselves were also 
usually opaque. Consequently the root-hairs were not easily 
traced down to their bases. They were distributed very unequally, 
being quite absent from the browner parts of the roots, while pre- 
sent on the parts which had remained pale-coloured. Notwith- 
standing this latter fact, it is very doubtful whether the rule of 
root-hairs arising almost exclusively from cells destitute of solid 
matter here holds good. 
Pelargonium zonale.— A fresh root was examined, and the cells 
contained no granules. It was then irrigated with a solution of 
7 to 1000, and in about 15 minutes granules could be distinctly 
seen in the exterior cells in alternate rows. Two other rootlets, 
after being left in water for 48 hours, were not at all affected. 
They were then irrigated with the same solution and reexamined 
after 24 hours; and now the exterior cells in rows, as well as those 
surrounding the vascular bundle, abounded with granular matter. 
Other roots were left for 48 hours in a solution of 4 to 1000; 
and the cells near their tips were so packed with dark-brown 
granular matter as to be blackened. Higher up the roots, the 
granules were pale brown, translucent, irregularly rounded, and 
often more or less confluent. In some dark-coloured rootlets the 
