shoots grow, must know, that they have advanced but a very short time before they begin to set out roots all round the parent bulb, which strike directly into the soil. At the first, their whole sustenance is derived from the potatoe; by and by they begin to draw a little nourishment from the soil; the proportion of nourishment they derive from the soil is increasing every day, while that which they get from the parent bulb is diminishing, till at length the last dies entirely, and they derive nothing but from the soil. This is exactly analogous to the nourishment of a lamb it lives at first on its mother's milk entirely; it then eats a little grafs along with the milk; and ere long the milk is dried up, and it lives wholly on grafs. May it not happen, then, that a very vigorous sprout, which has been produced from a large potatoe (and these are probably those which advance first), by being separated from the potatoe after it has been properly nursed, will (like a well-nursed lamb), if planted in a soil where it finds abundance of nourishment, continue to advance without suffering a great check, and keep the superiority that it has once obtained? From this circumstance it may happen, that in one particular case a very tolerable crop may be thus produced from sprouts; and I have scarcely a doubt but the experiment may be so managed, as that the crop from sprouts might be better than that from actual bulbs; though the real fact might be, that, taking things fairly upon accurate trials, the result, in general, would be ^ We cannot be too cautious about draw the reverse. ing general conclusions from particular facts, until they are fairly collated with others. I shall take an opportunity soon to point out some other peculiarities respecting the propagation of this valuable esculent, that may perhaps be applied on some occasions to useful purposes. NATURAL-HISTORY. ON THE TRANSFORMATION, &c. OF INSECTS. [Continued from page 197.] Not only are the diversities very great that are observable between the varieties of the same species of the larger animals on this globe, and of vegetables; but there is reason to believe, that a similar variation occurs in many cases with regard to insects also. As yet, however, we can speak with very little certainty respecting the varieties of any one species of insects, because these have hitherto scarcely attracted notice : but there can be no doubt, that when this subject comes to be properly inquired into, it will be found to open a source of considerable improvement in various respects. Dr. Anderson, of Madras, only a few years ago, introduced into Bengal a variety of the silk-worm, which undergoes all its changes in the space of one month, and therefore is susceptible of a kind of management that cannot apply to the silk-worm reared in Europe. All the insects that we have hitherto had occasion specifically to notice in our Recreations, proceed from eggs deposited by the parent; and it was for a long time as generally believed, that insects were produced from eggs only, as that quadrupeds were universally brought forth in a living form: but this rule is now found to admit of exceptions, and of exceptions among insects that so nearly resemble each other in their form, habits, and all their future transformations, as would entitle them to the name of varieties only of the same kind, were it not for this very striking diversity; a diversity, however, that is by no means obvious, and which, therefore, very long eluded the notice of the acutest observers of nature. There are few persons who do not know that the large blue fly, the Musca vomitoria,* is constantly on the watch during the summer months to deposit its eggs on the meat in our shambles and elsewhere, and that from these eggs proceed worms that tend much to deteriorate this kind of our food; but it is not so generally known, that there is another fly, the Musca carnaria,† which so nearly resembles the former, as not to be easily distinguishable from it by an inexperienced eye, which lays no eggs, but deposits its young in a living state upon the same meat, and which appears under the same worm-like form, feeds as it does, * Musca vomitoria, antennis plumatis pilosa thorace nigro, abdomine cœruled nitente. Linn. Syst. Nat. p. 989, n. 67. + Musca carnaria, antennis plumatis pilosa nigra, thorace lineis pallidioribus, abdomine nitidulo tefsellato, oculis rubris. Linn. Syst. increases in size, undergoes all the transformations so much in the same manner as the former, and finally appears in the fly state so little different from the other, that they are only to be discriminated by the keen eye of a well-informed naturalist: in short, these two kinds of insects differ much less perceptibly from each other, than a short-haired sheep does from a full wool-bearing sheep of any sort, or a shock dog from a greyhound. Redi (who above two hundred years ago, by a train of accurate observations and judicious deductions from them, did more than any other man ever did to eradicate those popular notions respecting spontaneous generation, and similar doctrines which ingenuity and indolence had devised as an apology for ignorance) had so far got a glimpse of this deviation from what he conceived to be a general law of nature, as to suggest it as an object that required farther elucidation; but it was reserved for Reaumur fully to develope this myse tery; and it is now established beyond a doubt, that not only these flies, but many others, are viviparous in the strictest sense of the word. We have already had occasion in this work (Vol. II. page 96) to remark the still more general exception to the usual course of nature in regard to the propagation of the aphides, which are at one season of the year oviparous, and at another viviparous, with several other singular diversities respecting the propagation of animals. Many are the circumstances that concur to mislead the young observer respecting the propagation of viviparous insects. We have in a former volume observed (Vol. III. p. 263), that the numerous and greatly diversified clafs of flies called ichneumon, are directed by an unerring instinct to deposit their eggs for the most part in the body of some insect or its larva, where they are hatched, where they feed upon the very substance of the animal itself, and from which they sometimes ifsue in their worm state after having attained their full size; nay, sometimes they undergo their final change in the body itself of the insect on which they have been fed, and come forth in their perfect imago, or fly state. Until this economy of nature was completely understood, it occasioned infinite perplexity in the minds of men on this subject; and metamorphoses little less wonderful than those of Ovid were seemingly realised, An animal was never, indeed, transformed into a tree; but a living worm was often supposed to be the parent of a living fly which was capable of performing all its functions in perfection the instant after it was born; while at other times the same worm was seen to produce other worms that became insects of a very dif ferent form, after having undergone another change, These perplexities are now clearly removed, and we are enabled to trace the progress of nature with a superior degree of intelligence. The circumstance just stated, however, tended, no doubt, to prevent for a long time the discovery of the viviparous nature of many insects; for when any one chanced to observe such flies deposit a living worm, it was not unnatural to suppose that this might be one of those parasitic insects which had been deposited in |