NORTH-INDIAN SPECIES OF IMPATIENS AS BORDER PLANTS. 197 
in fact, a peculiarity calculated especially to engage the attention 
of the fair sex ; and I would venture to assert, that many a de¬ 
licate admirer of floral beauties, whose eye had been attracted 
by the beauty of these plants, has been momentarily startled 
by the unceremonious discharge of a volley of— seeds. In the 
instance before us, this irritability is lodged in the valves of the 
fruit, which, when ripe, separate on the slightest touch, and 
spring back with great elasticity. It may be thus explained :— 
the tissue of the valves of which the seed-vessel is composed 
consists of cellules that diminish in size very gradually from 
the exterior to the internal surface; the fluids contained in the 
external cells are the most dense, and, by a process of endos- 
mose, they gradually empty the inner cells, and distend them¬ 
selves ; in consequence of this, the external tissue is disposed 
to expand, and the internal to contract, as soon as anything 
occurs to destroy the force that keeps them straight; and this 
at last does occur by the disarticulation of the valves, the pe¬ 
duncle, and the axis : a sudden spontaneous movement follows, 
and each valve rapidly rolls itself inwards, and with such force 
that the seeds are ejected to a considerable distance. Du- 
trochet, an extremely acute physiologist, has proved that it is 
possible to invert this phenomenon by producing exosmose : in 
order to effect this he placed fresh valves of Impatiens into 
sugar and water (a fluid denser than that contained in the 
valves), and this gradually emptied the external tissue, and, 
after rendering the valves straight, ultimately curved them back¬ 
wards. 
The species of Impatiens more immediately under our notice 
were, when first introduced, most generally cultivated in pots, 
in the same manner and situations as the common balsam. In 
such situations they are extremely beautiful, and deserving of 
very extensive cultivation ; in short, there is something so pe¬ 
culiarly interesting in the form of their floral parts, and in their 
profusion and elegant distribution, that I would even prefer 
them to the more commonly cultivated garden balsam. Beauti¬ 
ful and valuable as they undoubtedly are in such situations, 
these high qualities are increased in a tenfold degree by the 
facility with which they may be cultivated in the open ground: 
here they attain a vigour and robustness which marks it as a 
' situation peculiarly appropriate to them ; and it is in this sense 
