1854.] OF THE ROYAL INSTITUTION. 411 
of destination. Sir W. Hooker bears ample testimony to the suc- 
cess of the plan, and states that in about four years nearly three 
thousand plants have been despatched to different parts of the world. 
When Captain M‘Clintock left for the Arctic regions, a case con- 
taining British plants was entrusted to him, and, when last heard 
of, the plants had passed successfully through one polar winter. 
Having glanced at the various philosophical purposes to which 
these cases may be applied, such as observations upon the habits of 
plants in an undisturbed atmosphere, the value of different moulds, 
and the action of the several vital stimuli, and having exhibited a 
plant of Linaria Cymballaria in illustration of the effects produced 
by deficient light, the Lecturer proceeded to notice the application 
to animals and man. 
Philosophers have long been aware of the influence exerted by plants 
in counterbalancing the effects of animal respiration. Towards the end 
of the last century, Lavoisier led the way in determining what has been 
happily called ‘‘ nature’s balance,” by showing the exact changes 
produced in the atmosphere by the respiration of animals. Priestley, 
soon after, proved by experiments with growing plants in air that had 
been vitiated by respiration and combustion, that they restored air 
so vitiated to its original purity. Senebier demonstrated the precise 
action exerted by plants in decomposing carbonic acid and fixing the 
carbon and liberating the oxygen, and that this takes place in water 
as well as air. Boussingault further proved that plants decompose 
water, and, from this, furnish another source of oxygen to air that 
has been deteriorated by animal life. Now, these counterbalancing 
actions of animal and vegetable life which are ever going on in the 
world without, and which are among the greatest marvels in the 
economy of Nature, may be realised most completely in one of these 
cases. Mr. Ward felt this, and accordingly in 1841 established in 
his largest fern-house, in a capacious earthenware vessel given to 
him by Mr. Alfred White, an aquarium for fish and plants. In this 
vessel, which contained twenty gallons of water and which he sur- 
rounded with rock-work raised several feet above its margin, he 
placed gold and silver fish in company with several aquatic plants, 
viz. Valisneria spiralis, Pontederia crassipes, Pistia stratiotes, and 
Papyrus elegans. In this miniature lake, the water of which was 
never changed, but kept in a constantly pure state by the action of 
the associated plants, the animals lived in a healthy condition for 
many years. This aquarium or vivarium soon gave the hint to Mr. 
Bowerbank who procured a large glass-jar, in which he placed 
stickle-backs, minnows, and snails, with plants of Valisneria, and 
covered in the jar with a piece of glass. Mr. Mitchell of the Zoolo- 
gical Society states that the jar just noticed, gave him the suggestion 
for the interesting vivaria at the Gardens. Aquaria in open bottles 
would seem to have been ornaments of the philosopher’s study nearly 
a hundred years ago, as a coloured illustration in a work by Leder- 
miiller, published in 1763 wil) prove. All that Mr. Ward claims 
