AND AMERICAN RURAL SPORTS. 



weaker, so are these furnished with the most admirable 

 powers of evading their destroyers. In the economy of 

 insects, we constantly observe, that the means of defence, 

 not only of the individual creatures, but of their larvae and 

 pupse, against the attacks of other insects, and of birds, is 

 proportioned, in the ingenuity of their arrangements, to 

 the weakness of the insect employing them. Those species 

 which multiply the quickest have the greatest number of 

 enemies. Bradley, an English naturalist, has calculated 

 that two sparrows carry, in the course of a week, above 

 three thousand caterpillars to the young in their nests. 

 But though this is, probably, much beyond the truth, it is 

 certain that there is a great and constant destruction of 

 individuals going forward; and yet the species is never 

 destroyed. In this way a balance is kept up, by which 

 one portion of animated nature cannot usurp the means of 

 life and enjoyment which the world offers to another 

 portion. In all matters relating to reproduction, Nature is 

 prodigal in her arrangements. Insects have more stages to 

 pass through before they attain their perfect growth than 

 other creatures. The continuation of the species is, there- 

 fore, in many cases, provided for by a much larger number 

 of eggs being deposited than ever become fertile. How 

 many larvse are produced, in comparison with the number 

 which pass into the pupa state; and how many pupae perish 

 before they become perfect insects ! Every garden is cover- 

 ed with caterpillars; and yet how few moths and butter- 

 flies, comparatively, are seen, even in the most sunny 

 season. Insects which lay few eggs are, commonly, most 

 remarkable in their contrivances for their preservation. 

 The dangers to which insect life is exposed are manifold; 

 and therefore are the contrivances for its preservation of 

 the most perfect kind, and invariably adapted to the pecu- 

 liar habits of each tribe. The same wisdom determines the 

 food of every species of insect; and thus some are found to 

 delight in the rose-tree, and some in the oak. Had it 

 been otherwise, the balance of vegetable life would not 

 have been preserved. It is for this reason that the contri- 

 vances which an insect employs for obtaining its food are 

 curious, in proportion to the natural difficulties of its struc- 

 ture. The Ant-Lion is carnivorous, but he has not the quick- 

 ness of the spider, nor can he spread a net over a large 

 surface, and issue from his citadel to seize a victim which 

 he has caught in his out works. He is therefore taught to 

 dig a trap, where he sits, like the unwieldy giants of fable, 

 waiting for some feeble one to cross his path. How labori- 

 ous and patient are his operations — how uncertain the 

 chances of success! Yet he never shrinks from them, be- 

 cause his instinct tells him that by these contrivances alone 

 can he preserve his own existence, and continue that of his 

 species. — Lib. Ent. Knowledge. 

 C ■ 



BASIN OF THE MISSISSIPPI. 



IN A GEOLOGICAL VIEW. 



The hydrographical basin of the Mississippi displays, 

 on the grandest scale, the action of running water on the 

 surface of a vast continent. This magnificent river rises 

 nearly in the forty-ninth parallel of north latitude, and 

 flows to the Gulf of Mexico in the twenty-ninth — a course, 

 including its meanders, of nearly five thousand miles. It 

 passes from a cold arctic climate, traverses the temperate 

 regions, and discharges its waters into the sea, in the region 

 of the olive, the fig, and the sugar-cane. * No river afibrds 

 a more striking illustration of the law beforementioned, 

 that an augmentation of volume does not occasion a propor- 

 tional increase of surface, nay, is even sometimes attended 

 with a narrowing of the channel. The Mississippi is a 

 mile and a half wide at its junction with the Missouri, 

 the latter being half a mile wide; yet the united waters 

 have only, from their confluence to the mouth of the Ohio, 

 a medial width of about three quarters of a mile. The 

 junction of the Ohio seems also to j^roduce no increase, but 

 rather a decrease of surface.! The St. Francis, White, 

 Arkansas, and Red rivers, are also absorbed by the main 

 stream with scarcely any apparent increase of its width; 

 and, on arriving near the sea at New Orleans, it is some- 

 what less than half a mile wide. Its depth there is very 

 variable, the greatest at high water being one hundred and 

 sixty-eight feet. The mean rate at which the whole body 

 of water flows, is variously estimated. According to some, 

 it does not exceed one mile an hour. % The alluvial plain 

 of this great river is bounded on the east and west by 

 great ranges of mountains stretching along their respective 

 oceans. Below the junction of the Ohio, the plain is from 

 thirty to fifty miles broad, and after that point it goes on 

 increasing in width till the expanse is perhajjs three times 

 as great! On the borders of this vast alluvial tract are 

 perpendicular cliffs, or "bluffs," as they are called, com- 

 posed of limestone and other rocks. For a great distance 

 the Mississippi washes the eastern "bluffs;" and below the 

 mouth of the Ohio, never once comes in contact with the 

 western. The waters are thrown to the eastern side, be- 

 cause all the large tributary rivers enter from the west, and 

 have filled that side of the great valley with a sloping mass 

 of clay and sand. For this reason, the eastern bluffs are 

 continually undermined, and the Mississippi is slowly but 

 incessantly progressing eastward. § 



The river traverses the plain in a meandering course, 

 describing immense and uniform curves. After sweeping 



* Flint's Geography, vol. i. p. 21: t Ibid. p. 140. % Darby. 



^ Geograph. Descrip. of the State of Louisiana, by W. Darby, Philadelphia, 

 1816, p. 102. 



