Public Parks. 37 



beings to each other ; each removing from the atmosphere which 

 would be noxious to the other — each yielding to the atmosphere 

 what is essential to the continued existence of the other.* Little does 

 man think how dependent he is upon vegetation, for while the 

 vegetable kingdom is entirely independent, and might have existed 

 alone, yet it is absolutely essential to the life of man.f 



I 



AQUATIC VEGETATION. 



The remarks thus far made, generally apply to the vegetable 

 kingdom, and have mainly had reference to the higher orders of 

 plants. I now propose to advert to the lower orders which occur in 

 water, both fresh and salt, and play the same part in the economy of 

 nature as those found on land. They have been found in countless 

 myriads in the depths of the ocean, far down as the plummet has yet 

 sounded, and in fact, may be said to be found in every climate under 

 one phase or another. | The sea teems with animal life, and without 



* Gray's Structural Botany. 



t It has been found by experiment that plants will thrive in ak containing more carbonic acid than 

 that usually found in the atmosphere when exposed to a strong sun-light, or in climates where the solar 

 light is not much obscured by clouds. The floating islands which are constantly being found in the lake 

 of Solfatara, in Italy, according to Sir Humphrey Davy, exhibit a striking example of cryptogamic 

 vegetation in an atmosphere impregnated with carbonic acid. These islands consist chiefly of confervs 

 and other simple cellular plants, wliich are copiously supplied with nutriment by carbonic acid tliat is 

 constantly escaping from the bottom of the lake, with a violence that gives to the water an appearance of 

 ebullition. Dr. Schleiden, Weigmati's Archives, 183S, mentions that the vegetation around the 

 springs in the valley of Gottingen, which abound in carbonic acid, is very rich and luxuriant ; appearing 

 several weeks earlier in spring, and continuing much later in autumn, than at other spots in the same 

 district. Humboldt says that "exhalations of carbonic acid (mofettes) are, even in our days, to be 

 considered as the most important gaseous emanations, with respect to their number and the amount of 

 their effusion. We see in Germany, in the deep valleys of Eifel, in the neighborhood of Lake Laach, in 

 the crater-like valley of the Wehr of Western Bohemia, exhalations of carbonic acid gas manifest 

 themselves as the last efforts of volcanic activity, in or near the foci of an earlier world. In these earlier 

 periods, when a higher terrestrial temperature existed, and when a great number of fissures remained 

 unfilled, the processes we have described acted more powerfully, and carbonic acid and hot steam were 

 mixed in larger quantities in the atmosphere, from whence it follows, as Adolph Brongniart has 

 \n%^xi\ovL^y A\Q\sxi,fyci\}a^ Aiinales ties Scietices Naturelles,) \\\3.\. the primitive vegetable world must 

 have exhibited, almost everywhere, and independently of geographical position, the most luxurious 

 abundance and the fullest development of organism. In these constantly warm and damp atmospheric 

 strata, saturated with carbonic acid, vegetation must have attained a degree of vital activity, and derived 

 the superabundance of nutrition necessary to furnish material for the formation of the beds of lignite, 

 (coal,) constituting the inexliaustible means on which are based the physcial power and prosperity of 

 nations." # # # 



"That portion of the carbon which was not taken up by the alkaline earths, but remained mixed with 

 the atmosphere as carbonic acid, was gradually consumed by the vegetation of the earlier stages of the 

 world, so that the atmosphere, after being purified by the processes of vegetable life, only retained the 

 small quantity which it now possesses, and which is not injurious to the present organization of animal 

 life." — Cosmos. Daubney, in his work on "Volcanoes," says, speaking of the Lake of Laach, that 

 "the thickness of the vegetation on the sides of its crater-like basin, renders it difficult to discover the 

 nature of the subjacent rock." The same writer, in his " Report to the British Association," for 1849, 

 of experiments made by him, confirms, to a great extent, the ingenious hypothesis of M. Brongniart. 



t Although the surface of the ocean is less rich in living forms than that of continents, it is not 

 improbable that on a farther investigation of its depths, its mterior may be found to possess a greater 

 richness of organic life than any other portion of our planet. Charles Darwin, in the agreeable naiTative 

 of his extensive voyages, justly remarks that our forests do not conceal so many animals as the low, 

 woody regions of the ocean, where the sea-weed rooted to the bottom of the shoals, and the several 

 branches of foci loosened by the force of the waves and currents, and swimming free, unfold their 

 delicate foliage, upborne by air cells. — Costnos. 



