



BOTANY. 319 



a very useful little scavenger, whose beneficial functions have been 

 too much over-looked in the economy of animal life, viz., the water 

 snail. The natural food of these animals is the very green mucus and 

 decaying vegetable matter, which threatened to destroy the object of 

 the experiment. Five or six of these creatures, the Himnoea stagnate, 

 were consequently introduced, and by their rapid and continued loco- 

 motion, and extraordinary velocity, soon removed the cause of inter- 

 ference, and restored the whole to a healthy state, thus perfecting the 

 balance between the animal and vegetable inhabitants, and enabling 

 both to perform their functions with health and energy. The vallis 

 neria attained to a luxuriant and healthy growth, the fish appeared 

 lively and bright in color, while the snails, judging from the enormous 

 quantities of eggs deposited by them, appeared to thrive wonderfully, 

 and besides their functions in sustaining the perfect adjustment of the 

 series, afforded large quantities of food to the fish in the form of young 

 snails, which are devoured as soon as they exhibit signs of vitality, 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 young snails, and excretes materials well 

 adapted for the food and growth of the plant. The plant, by its res- 

 piration, consumes the carbonic acid produced by the fish, appropriat- 

 ing the carbon to the construction of its tissues and fibres, and liber- 

 ates oxygen in its gaseous state to sustain the healthy functions of 

 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, pre- 

 serving the water in a clear and healthy condition. The slimy snail, 

 finding its proper nutriment in the decomposing vegetable matter, 

 prevents its accumulation by removal 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, whilst it also acts the important part of a purveyor to its finny 

 neighbor. 



INFLUENCE OF SOLAR RADIATIONS ON PLANTS. 



AT the British Association, Belfast, Dr. J. H. Gladstone made a 

 report on the influence of the solar radiations on the vital powers of 

 plants growing under different atmospheric conditions-. As a prelim- 

 inary matter of inquiry, the mere effect of colored media in accelerat- 

 ing or retailing the growth of various kinds of plants was tried. Hya- 

 cinths were chosen as the sample of bulbous-rooted plants. Roots of 

 as nearly as possible the same size and description in every respect 

 were grown under the various bell glasses. Certain differences were 

 described, both in the rootlets and the leaves, which might fairly be 

 attributed to the character of the light ; the time of flowering, and the 

 flowers themselves, were not affected by it ; and the greatest growth, 

 (estimated quantitatively in each instance,) took place in the plant 

 28 



