drew them from their cells, and satisfied himself that there was an incipient vegetation, and moreover that its progress had kept pace with the growth of the chrysalis. It was remarked, that rarely or never was there more than one vegetable on a single wasp.

He then satisfied himself why the vegetable parasite was situated on the fore-part of the body. Botanists have pronounced this production to be a species of Sphæria, belonging to the natural order of Fungi. Upon the supposition that it is propagated by seeds in the ordinary mode, these seeds would naturally alight upon the most exposed part of the unhatched insect that was accommodated for their reception. This would of course be near the head. Being fixed there, it would increase with the enlargement of the animal, and drawing nourishment from its body, would continue to grow even after it had attained its last and perfect state, until the Spharia had destroyed the life of the wasp.

The mind becomes reconciled to the idea of a vegetable sustaining itself upon a living animal, by considering the history of the Ichneumon, an insect of the Hymenopterous order. It is called pupivorous, on account of the voracity with which its larvæ devour the larvæ, chrysalids, and even eggs of other insects, more especially those of the Lepidopterous order. Some of them penetrate the bodies of their prey, and, with their numberless brood, slowly consume, and at last kill them; while others, the Ophions, are attached to the skin of the larva by the footstalk of a cocoon, through which their heads pierce the internal parts, while their tails remain in their own inclosures. This operation frequently continues until the large invaded larva completes its cocoon, when it dies consumed and exhausted. After this, the family of ichneumons come forth, first bursting their own cocoons, and then that of their prey. It is also stated as a fact, that one species of Ichneumon sometimes destroys the larvæ of another species of the same genus. These occurrences furnish strong and instructive analogies.

Here we find that the living bodies of caterpillars and their chrysalids, are the habitations and nurseries of other insects, the Creator having arrayed one tribe against another, apparently for the purpose, among others, of putting a limit to their own

excessive multiplication. There seems also to be another check upon their inordinate increase. The fungous tribes of vegetables are in various instances the destroyers of the insect race. Their germs or seeds, conveyed by the winds or otherwise to the surface of these creatures, find them to be situations fit for their adhesion.

If it now may be considered as certain, continues Dr Mitchill, that a vegetable may grow upon the larva or chrysalis of a wasp, and continue to increase until they change into the complete or imago state, and after, why may not the like happen to the larva and chrysalis of the Sphynx and Melolontha? The presumption is strong, that the seeds were scattered on the back and sides of the larvæ, exposed everywhere to their influence, and not incased and protected like the young wasps. Whence it might be inferred they would germinate and enlarge until after the beginning of the fourth metamorphosis, when they would probably overcome their supporter.

Dr Maddiana, however, thinks, that, in some instances, the ́vegetation commences only after life has ceased. Dr Mitchill continues to adduce instances of vegetable substances issuing from the bodies of insects; and in conclusion draws the following inferences: 1. That this kind of vegetation is not confined to a single species of insect, but obtains in several, viz. the Wasp, Sphynx and Melolontha, there being also reason to suppose that it extends to others: 2. That the bodies of insects nourish more than one species of vegetable, as the Sphæria, Clavaria, and probably others not yet investigated: 3. That a part, at least, of this order of parasitical vegetables, begin their work of annoyance, like the larvae of the ichneumon, in the body of the living insect, and continue it until the creature is killed by its destructive inroads: 4. That these mixed associations of vegetable with animal matter, are not prone to rapid putrefaction, but remain long enough to be collected by naturalists, and become the objects of scientific inquiry.

The chief or leading fact intended to be established, is the derivation of nourishment by the vegetable from the living animal, which the Doctor thinks may be rendered more admissible, when we reflect that the bodies of dead animals support vegetation, in the form of manure and otherwise, and that many

Crustacea and Mollusca are invested with a dense vegetable covering.

On the relative Proportions of certain parts of the Eye of the Fatus, compared with the same parts of the perfectly developed Eye. By Professor CARUS.

THE

HE remark has already been made by some anatomists and physiologists, that the human eye, as well as all the organs, runs through a series of degrees of development, in which its analogy with the eye of animals is so much the greater, the nearer it is to its first formation. The object of Professor Carus, in his memoir, is to follow out this proposition in some of its details. The following are among the most interesting results of his investigation.

The eye of man, compared with that of animals, presents the most extended retina, in proportion to the size of the eye-ball (consult Sömmering's Plates, De Oculorum hominis animaliumque sectione horizontali, Götting. 1818). The vitreous

body of the human eye is the largest of all, compared with the bulk of the crystalline humour: the portion of the eye-ball which covers the transparent cornea, and which allows the iris and pupil to appear, is smaller in proportion to the part which the sclerotic covers; and this proportion is modified only in birds, especially the birds of prey, in which the extraordinary breadth of the ciliary processes puts limits to the extension of the retina, which is kept at a distance from the edge of the cornea. In the eye of animals, also, the sclerotic scarcely appears under the palpebræ, while a considerable portion of it is visible in the human eye.

It is equally observed, in the different forms of the latter, that the relation of the extent of the iris and pupil, to the surface of the visible portion of the sclerotic, is not always the same. In children, the iris and pupil have a greater proportional extent, exhibiting an analogy with the eye of animals; and in adults a large iris with its pupil, seems to us rather to be the expression of physical power, while an eye in which the contrary takes place, and in which the sclerotic coat shews itself to a great

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extent, expresses rather something spiritual or celestial. The pious painters of the old Italian and German schools had a clear idea of this proportion, and in their representations of eyes of virgins, angels, Christ, and saints, it may be seen that the pupil and iris are smaller in relation to the sclerotic, than they are in well formed ordinary eyes. From this it may be presumed, that the eye of the fœtus_will equally present modifications in the proportion of the parts of which it is composed. The results which M. Carus has obtained, in consequence of accurate measurements, are the following:

It is seen from this, that the proportion of the breadth of the iris to that of the globe of the eye, as well as that of the iris to the axis of the eye-ball, increases with age. The following is another table, which presents some points of comparison with the eye of animals:

There results from all this, that the eye of the fœtus only assumes by degrees the proportions that obtain in the eye of the adult; and that the smallness of the iris, in proportion to the * Brochet, Esox lucius, Linn.

Mr Don on the irritability of the Stigma in Pinus Larix. 43 diameter as well as to the axis of the ball of the eye, is one of the characters by which the fully developed human eye is distinguished, both from the eye of the foetus, and from that of animals.

On the Irritability of the Stigma, and on the origin and nature of certain parts of the Fructification in Pinus Larix. By Mr DAVID DON, Libr. L. S., Member of the Imperial Academy Naturæ Curiosorum, of the Royal Botanical Society of Ratisbon, and of the Wernerian Society of Edinburgh, &c. (Communicated by the Author).

IT is a well known fact, that certain plants themselves, but more generally particular organs, are endowed with a species of irritability analogous to that observable in the animal kingdom. While engaged in examining the female flowers of the common Larch, during the last spring, in order to satisfy myself respecting the real nature of the stigma, I was much surprised by the remarkable degree of irritability observable in that organ, a circumstance which I am not aware had ever been before noticed. That the cucullate processes at the base of the ovaria are the true stigmata, is a point so fully established, as to render unnecessary any additional facts in its support. To regard the ovaria as naked ovula, and that impregnation takes place by the pollen being immediately shed on their surface, instead of being conveyed by means of an organ analogous to the stigma of other plants, are opinions by far too paradoxical to admit of belief. These cucullate processes, when fully mature for the reception of the pollen, expand, and their inner surface is then clothed with innumerable minute papillæ. I took a branch bearing unimpregnated female flowers, and having dusted them with the pollen from the ripe male catkins of another branch, I found on examination the cucullate stigmata completely filled with the pollen, and I could readily perceive the sides of the female organ contract gradually, until they finally became completely collapsed. The pollen in Conifera being composed of minute vesicles filled with a prolific fluid, the collapsing of the sides of the stigmata is evidently for the purpose of pressing out the contents of these vesicles, and forcing the fluid through the narrow duct on to the

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