1-22 THE FLORIST. 



healthy hfe of the fish must have suffered, and probably their vital 

 functions have been destroyed. The removal of these decaying 

 leaves from the water, therefore, became a point of paramount im- 

 portance to the success of the experiment. To effect this, I had 

 recourse to a very useful little scavenger, whose beneficial functions 

 have been too much overlooked in the economy of animal life — I 

 mean the water-snail, whose natural food is the very green slimy 

 growth, or mucus, and decaying vegetable matter, which threatened 

 to destroy the object which was wished to be obtained. Five or 

 six of these creatures — the Limnsea stagnalis — were consequently 

 introduced, and, by their continued and rapid locomotion and ex- 

 traordinary voracity, soon removed the cause of interference, and 

 restored the whole to a healthy state ; thus perfecting the balance 

 between the animal and vegetable inhabitants, and enabling both to 

 perform their vital functions with health and energy. 



So luxuriant was the growth of the Vallisneria under these 

 circumstances, that, by the autumn, the one solitary plant that had 

 been originally introduced had thrown out myriads of offshoots and 

 suckers, thus multiplying to the extent of upwards of thirty-five 

 strong plants ; and these threw up their long spiral flowering stems 

 in all directions, so that at one time more than forty blossoms were 

 counted lying on the surface of the water. 



The fish have been lively, bright in colour, and appear very 

 healthy; and the snails also — judging from the enormous quantity 

 of gelatinous masses of eggs which they have deposited on all parts 

 of the receiver, as well as on the fragments of stone — appear to 

 thrive wonderfully, and, besides their functions in sustaining the 

 perfect adjustment of the series, afford a large quantity of food to 

 the fish in the form of the young snails, which are devoured as soon 

 as they exhibit signs of vitality and locomotion, and before their 

 shell has become hardened. 



Thus we have that admirable balance sustained between the 

 animal and vegetable kingdoms, and that in a liquid element. The 

 fish, in its respiration, consumes the oxygen held in solution by the 

 water as atmospheric air, furnishes carbonic acid, feeds on the insects 

 and young snails, and excretes material well adapted as a rich food 

 to the plant, and well fitted for its luxuriant growth. 



The plant, by its respiration, consumes the carbonic acid pro- 

 duced by the fish, appropriating the carbon to the construction of 

 its tissues and fibre, and liberates the oxygen in its gaseous state to 

 sustain the healthy functions of the animal life, at the same time 

 that it feeds on the rejected matter which has fulfilled its purposes 

 in the nourishment of the fish and snail, and preserves the water 

 constantly in a clear and healthy condition. While the slimy snail, 

 finding its proper nutriment in the decomposing vegetable matter 

 and minute confervoid growth, prevents their accumulation by re- 

 moving them from the field, and, by its vital powers, converts what 

 would otherwise act as a poison into a rich and fruitful nutriment, 

 again to constitute a pabulum for the vegetable growth, while it also 

 acts the important part of a purveyor to its finny neighbours. 



