JUNE. 
129 
instruction. It is not sufficient for horticul¬ 
turists merely to see—they must also study 
and reflect. Neither is it sufficient for bo¬ 
tanists to observe details minutely ; they must 
also see the plants on a large scale, and in 
grouped masses. The connection of Practice 
with Theory, and of Art with Science, is ac¬ 
knowledged to be indispensable; and in ac¬ 
cordance with this prevalent opinion we here 
affirm, by our presence in this room, the 
necessary union of Botany and Horticulture. 
The aim of my brief observations will be to 
call to mind how they aid each other, and to 
show how much more they might do so. If 
«* I am not mistaken, it will follow from facts 
to which I shall allude, that our united efforts, 
scientific or practical, modest though they ap¬ 
pear, contribute to increase the well-being of 
man in all conditions and in all countries. 
Firstly, the Advantages of Horticul¬ 
ture to Botany. —Let us first mention the 
services that horticulture renders, or may 
render, to botany. Without being myself a 
horticulturist, I affirm or recognise them 
willingly, the advancement of science ren¬ 
dering it necessary to have recourse to all 
its collateral branches. 
We no longer live in those times of illusion 
when botanists merely occupied themselves 
with European plants, or with a few from the 
East, and, from a spirit of caution rather than 
from ignorance, pictured to themselves all dis¬ 
tant countries as possessing much the same 
general vegetation, with a few uncommon or 
exceptional species. A century of discovery 
has made known the extreme variety in the 
Floras, the restricted limits of many species, 
and the complicated entanglement of their 
geographical distribution. To see all the 
different forms of vegetation of the world, 
one would realise in a degree the history of 
the Wandering Jew ; besides, with this con¬ 
stant travelling, where would be the oppor¬ 
tunities for that reflection or study which 
create true science ? 
The traveller is too much exhausted in warm 
countries, too distracted in those temperate 
regions favourable to active life, and his facul¬ 
ties are too much benumbed in the colder re¬ 
gions, to enable him to devote himself to mi¬ 
nute researches with the lens or the micro¬ 
scope, or even to sketch or properly describe 
that which he has gathered. He sees, in 
passing, a crowd of things, but he can scarcely 
ever stop to enter into details, especially of 
those that come in rapid succession. Barely 
can he see the fruit and flower of a species at 
the same time, and it is quite impossible for 
him to study their complete development 
during the whole year. The notes taken by 
the most intelligent naturalist are so affected 
by these fatal circumstances, that it is seldom 
they add anything to that which a dried speci¬ 
men can teach the sedentary botanist. 
It is horticulture, then, which brings before 
us a multitude of exotic plants in a condition 
best adapted for study. Thanks to the variety 
of species it accumulates and successfully cul¬ 
tivates, the botanist can investigate the most 
difficult questions, and pursue his researches 
in families whose genera are not indigenous 
in Europe. In the herbarium, more minute 
observations can be made than is generally 
supposed ; nevertheless, for certain researches, 
it is absolutely necessary to have the living 
plant, particularly for those relating to rela¬ 
tive disposition, the origin and development 
of the several organs, as well as for studying 
the curious phenomena of fertilisation, the 
movements and direction of the stem, leaves, 
and parts of the flowers. Horticulture has 
done much to advance the progress of physi¬ 
ological botany, but it still has much to do. 
The most remarkable experiments of physi¬ 
ologists— viz., those of Hales, Duhamel, 
Knight—have been made in gardens. Also, 
the long series of experiments of the younger 
Gaertner, and, more recently, of M. Naudm, 
on hybridisation, which relate to the cardinal 
subject of the species. As much may be said 
of the numerous trials which are made, in 
horticultural establishments, to obtain new 
races or varieties. These have a great scien¬ 
tific importance, and it is undoubtedly the hor¬ 
ticulturists who are the teachers of botanists 
on these subjects. 
It appears to me, however, that gardens 
can be made still more useful in carrying out 
physiological researches. For instance: there 
is much yet to be learnt on the mode of ac¬ 
tion of heat, light, and electricity upon vege¬ 
tation. I pointed out many of these deficien¬ 
cies in 1855, in my “Geographie Botanique 
Baisonnee.”* Ten years later, Mr. Julius 
Sachs, in his recently published and valuable 
work on physiological botany, + points out 
much the same deficiencies, notwithstanding 
that some progress has been made in these 
matters. The evil consists in this, that when 
it is desired to observe the action of tempe¬ 
rature, either fixed or varied, mean or extreme, 
or the effect of light, it is exceedingly diffi¬ 
cult, and sometimes impossible, when obser¬ 
vations are made in the usual manner, to eli¬ 
minate the effects of the constant variations 
of heat and light. In the laboratory it is 
possible to operate under more exactly de¬ 
fined conditions, but they are rarely sufficiently 
persistent; and the observer is led into error 
by growing plants in too contracted a space, 
either in tubes or bell-glasses. This last ob¬ 
jection is apparent when it is wished to ascer¬ 
tain the influence of the gases diffused in the 
atmosphere around plants, or that of the 
plants themselves upon the atmosphere. 
Place plants under a receiver, they are no 
longer in a natural condition; leave them in 
the open air, and the winds and currents, pro¬ 
duced at each moment of the day by the tem- 
* Pages 46, 49, 57, and 1846. 
+ “Handbuch der experimental-physiologie der 
pfiar.zen,” 1 vol. in 8vo. Leipsig. 1865. 
