L. A. Boodle . 
40 
with a solution of sodium chloride, that this salt had been absorbed 
by the plants. 1 
Having seen specimens of the wall-flower with some of their 
leaves strongly succulent in a garden close to the sea, 2 I made some 
experiments in order to determine whether the same character could 
be induced in this species by treatment with sea-salt as in Lesage’s 
experiments. 
A number of plants of the garden Wall-flower were grown in a 
bed at Kew 3 during the year 1903. Both first and second 
years’ plants were used, and four of each were treated with salt, 
the rest of the plants being reserved for comparison. The method 
used was that of spraying the plants with a solution of Tidman’s 
sea-salt of normal strength, 4 and in such a manner that nearly all 
the spray was expended on the leaves and very little reached the 
soil. This treatment was begun on June 22nd and was repeated 
every few days until August 6th (the average interval being four- 
and-a-half days). One of the seedlings died, but two of the 
remaining three 5 and all of the four older plants produced a certain 
number of strongly succulent leaves in a fairly short time, while the 
control plants produced none. The change to the succulent 
character sometimes began at the tip of the leaf, but the leaves 
finally became thickened throughout their length, and this often 
occurred in leaves which appeared mature before the treatment was 
begun. A week was the shortest space of time in which distinct 
thickening was seen to take place. The succulent leaves agree 
closely in external appearance and in structure with those belonging 
to the Wall-flowers near the sea. They are brittle, yellowish-green 
internally, often strongly curved (viz: gutter-shaped with the 
1 Lesage, Le cklorure de sodium dans les plantes, Comptes 
rendus, tome 114, p. 143. 
2 I am obliged to my sister. Miss Edith Boodle, for having 
drawn my attention to these plants. 
2 I am indebted to the Staff of the Royal Botanic Gardens for 
the necessary facilities. 
1 Which is probably of about the same strength as sea water. 
This did not appear to injure the leaves or the growth of 
the plant, except on one or two occasions, when the tips of 
the younger leaves were “ burnt" by the salt- Coupin (Sur 
la toxicite du clilorure de sodium et de l’eau de mer it 
l’6gard des veg6taux, Revue Gen^rale de Bot., X., 1898, p. 
177) found that, for plants germinated in the manner of 
water-cultures iu water containing sodium chloride, a toxic 
effect was reached when the concentration amounted to 
about 1.5% for inland-plants (5 genera tried), about 3—4%, 
for maritime plauts (3 genera tried). The concentration of 
this salt in the Mediterranean is about 2.9 0 / 0 . 
4 The other seedling will be referred to separately below. 
