Succulent Leaves in the Wall-Flower. 43 
what amount of salt reached the roots, it is not advisable to draw 
any conclusions from this experiment. 
In the leaves of the different plants experimented on, the 
presence of chlorine and of sodium was tested by nitrate of silver 
and by a flame-reaction, respectively. Watery extracts (obtained 
by boiling) from equal weights of the normal leaf (not sprayed), the 
leaf of the resistant plant (sprayed) and the succulent leaf (sprayed) 
were compared. On addition of nitrate of silver practically no 
precipitate was given by the extract from the normal leaf (A), but 
fairly heavy and about equal deposits of chloride were yielded by 
the resistant (B) and the succulent (C) leaves. A similar result was 
obtained by cutting sections of fresh leaves and mounting them in 
a solution of nitrate of silver, the precipitate in B and C being 
fairly uniformly distributed throughout the mesophyll and epidermis. 
In the case of the sodium-flame reaction (obtained by burning part 
of a leaf and holding the ash in a bunsen-flame 1 ) the result was as 
follows. The normal leaf showed only slight sodium contents, the 
other leaves very considerable amounts, the succulent leaf giving a 
decidedly brighter flame than the resistant leaf. The succulent leaf 
need not, however, contain more sodium than the resistant leaf per 
unit of weight, though it probably does per unit of length. 2 
The experiments made last year on the Wall-flower were of a 
rough'preliminary nature, but I hope later to carry out more precise 
and extensive experiments. 
The results so far obtained show that in this plant succulence 
is readily induced by the action of sea-salt, and one may fairly 
safely assume that, in the experiments, the salt was chiefly absorbed 
through the leaves. The further result is obtained that, in a plant 
differing only slightly from the typical form, a large amount of salt 
may find its way into the leaves without bringing about this effect 
to the same extent, or, at any rate, so quickly as in the normal form. 
The cultivated Wall-flower is an instructive plant for experiments 
under varied treatment, for, besides growing under its normal meso- 
phytic conditions, and enduring severe treatment with salt, it can 
also grow as a xerophyte, e.g. on walls, where it has no soil other 
than the mortar. 
We may now refer to the structure of the leaves of Wall-flowers 
1 This was also examined spectroscopically. 
2 The plant salted through the soil gave a fairly bright sodium- 
flame, but less so than the resistant plant. 
