« AnteriorContinuar »
us impossible that these substances could be dissolved in water-the strongest fire we can create is alone sufficient for the purpose-wherefore it has been concluded, that all these substances have been some time liquefied in fire. Another doubt is respecting the form and situation of these Rocks, whether they are as they were first deposited, or whether their shape and place have been subsequently changed. There is ample reason to believe the latter. "On the origin of Granite, geologists widely differ. As it constitutes the basis upon which all other rocks appear to lie, Werner has regarded it as the first formation of that chaotic, rock-depositing fluid in which he imagines the earth once to have been enveloped. But many peculiarities of Granite have been deduced by Dr. Hutton as contrary to such an opinion. If we examine a granitic district in nature, we shall observe in regard to it, two leading phænomena. The one is, that veins of Granite frequently shoot from the great mass, into the superincumbent strata. The other that the bodies lying upon Granite, especially if they be stratified, either bear evidence of having been broken up, dislocated, and penetrated by the Granite whilst in a fluid state, or they seem as if gradually elevated by some power which has thrown the Granite up from below. So that upon this view of the subject, the date of Granite, as far as concerns its present position, is posterior to that of the strata that rest upon it. They were first deposited, and the Granite then erupted from beneath, and elevated the other strata, throwing them out of the horizontal, and giving them various inclinations to the horizon, and sometimes a vertical position.". ANNE. I believe I do not quite understand this question.
MRS. L.-It is simply this-whether the strata, that now lie above the Primitive Rocks, were once flat, and were broken and forced into their present form by the throwing up of the Granite from under them-or
whether the Granite having its present form before these were deposited upon it, they gradually assumed the shape of the mould on which they fell. This is a question we cannot answer. Certain it is, that every thing wears the appearance of violence and change.
As we proceed, we shall see ample reason to believe that the ocean has changed its bed-that the now dry land has been some time covered with water, and that more than once.
MAT.-But if more than one such flood had taken place, would it not have been recorded.
MRS. L.-Most likely, if it had occurred since the race of man became the inhabitants of earth.
MAT. But were not the earth and man created at the same time? When then could these things happen? MRS. L.-Moses, the historian of divine truth, has told us that in the beginning God made the earth, and it was without form and void. The earth, therefore, existed before it assumed its present form at the successive commands of the divine word. Moses does not tell us what was the condition of the earth while the darkness was upon it, nor how long it remained in that - condition, nor what changes it underwent before the Almighty commanded the light to shine upon it. Whatever was the condition of the earth before the six days' work of creation began, Moses, who did not mean to teach us Geology, or any thing but the history of our race, thought it enough to tell us that God had made it. If, therefore, Geology could prove that the earth has subsisted millions of years, instead of the thousands that our present race has dwelt upon it, it could not invalidate the truth of the Mosaic Scriptures. In the beginning, whenever that beginning was, God created it-and when it pleased him he made it what it is: and in the manner that he himself relates, prepared it for the reception of the beings he intended to place upon it. If any thing we discover in nature seems inconsistent with this relation, we may be assured it is our mistaken
understanding of his words, and not the words themselves, that are contradicted by the facts Geology has disclosed.
SERIES OF FAMILIAR CONVERSATIONS ON THE ANIMAL KINGDOM.
CLASS ARTICULATA-SUB-CLASS INSECTS.
Insects in their Pupa State.
ANNA. Is it convenient to you, papa, to renew the subject we were conversing on last evening? PAPA.-Yes, my dear; perfectly so. speaking, I recollect, of insects in their larva state. ANNA.-Yes, papa.
PAPA. We have taken a view of them then in that which is generally by far the longest, but by no means the most interesting part of their existence.
ANNA.-How long do they continue in that state?
PAPA.-The length of time varies considerably: some continue in it only a few days or weeks; others several months or years. When they are about to enter their third state they cease eating: some wrap themselves up in silken webs; others conceal themselves in decayed wood or in the earth; some take up their residence in the hollow stalks of plants; and many are concealed under leaves, or suspend themselves in dark places where they cannot easily be seen; and their skin, separating once more, discloses an oblong body, which Linnæus called a pupa, from its resemblance in miniature to a child trussed up like a mummy in swaddling clothes; as young infants used to be in this country, and still are in many parts of the Continent. Pupa, you know, is a Latin word for baby. In this state most insects eat no food, are incapable of changing their
place, and when touched shew no other signs of life but that of giving their abdomen violent contortions. If opened, they seem filled with a watery fluid, in which no distinct organs can be traced. The shape, however, of the pups of different tribes varies considerably; and as I have, I believe, told you, different names have been applied to them. "Those of the beetle and bee tribes are covered with a membranous skin, inclosing in separate and distinct sheaths the external organs, as the antennæ, legs and wings; which are consequently not closely applied to the body, but have their form for the most part clearly distinguishable: to these Aristotle originally gave the name of nymphe, which was con- tinued by Swammerdam and other authors, and has been adopted by many English writers on insects. Butterflies, Moths, and some of the two-winged tribe are in their pupa state also inclosed in a similar membranous envelope; but their legs, antennæ, and wings, are closely folded over their breast and sides; and the whole body inclosed in a common case or covering of a horny consistence, which admits a much less distinct view of the organs beneath it. As these pupæ are often tinged of a golden colour, they were called from this circumstance chrysalides by the Greeks, and aurelie by the Romans: both which terms are in some measure become anglicized; and though not strictly applicable to ungilded pupæ, are now given to those of all lepidopterous insects."
ANNA.-What are lepidopterous insects, papa?
PAPA.-Lepidopterous means scaly-winged: it is a name applied to those whose wings are covered with what appears a fine powder, such as moths and butterflies. The pupa of flies, and some other two-winged genera, which are not excluded from the skin of the larva, but remain concealed under it till the perfect insect bursts forth, are called cased-nymphs: those of grasshoppers, locusts, and others of that sort, that resemble the perfect insect except in having only the rudi
ments of wings, which are bound down under a skim that keeps them confined, are called semi-nymphs; these can eat and move as well while in the pupa state as when they have attained perfection: and those which, still more nearly resemble the perfect insect, undergoing but slight changes either in their external or internal conformation, and retaining, throughout the course of their metamorphoses, the same power of moving and eating, are termed by Linnæus complete pupa. The pupe of fleas, lice, and many other wingless insects, are of this kind..
ANNA. Now, papa, let me try if I can repeat the names of the different species of pupae; I think there are five: the chrysalis, the nymph,, the cased-nymph, the semi-nymph, and the complete pupa,
PAPA. Good girl; you have repeated them very correctly. The larva of the butterfly becomes a chrysa-. lis; that of the beetle and the bee, a nymph; that of the fly, a cased-nymph; that of the grasshopper, a seminymph; and that of the flea, a complete pupa. The envelope of cased-nymphs, which, as I said before, is formed of the skin of the larva, considerably altered in form and texture, is called the puparium; while the artificial, coverings of different kinds, whethen of silk, wood, or earth, which many insects fabricate for them selves previously to assuming the pupa state, is termed
ANNA. Are there any other insects besides silkworms that form for themselves silken, coverings,?
PAPA. Yes, many do, both during their larva state and previously to assuming the pupa: there are none, however, whose production is so valuable to us. The Tinea, or clothes' moth, as soon as it comes into, exist. ence, manufactures for itself a thick, warm coat of wool: or hair, curiously incorporated with silk drawn from its own mouth and another species of Tinea, which may often be found on the under surface of the leaves of the pear-tree in the spring, constructs its habitation entirely