the inquirer to follow them throughout their developmental career to ultimate perfection in the imago; and in them also may be seen to commence anew the life cycle dating from the deposition of ova. This rare privilege of tracing insect metamorphosis is not afforded however, even under the most favorable circumstances, without great risk of self deception on the part of the investigator.

Of phosphorescent Lampyridæ in the south-western part of the Atlantic district I am acquainted with eight species; two of these have apterous females, which are also distinguished by other peculiarities. In this article I shall assume their origin from a common type, which by a series of progressive and retrograde steps have given rise to their present forms.

Buffon's assertion that "nothing in nature is so permanent as type," is well sustained in the known tendency of both plants and animals, when not influenced by extraneous causes, to return to an original model; while on the other hand this very inclination to resume a certain form implies a capability of change.

"Whenever," says Humboldt, "a new element develops itself in the feelings of mankind, it may almost invariably be traced to an earlier, deep-seated, latent germ." What this great writer said of the emotional nature, will probably apply with equal force to the development of physical structures and functions. The capability of adapting or evolving these is the "deep-seated, latent germ" which is a positive power residing in animal forms, only awaiting the given conditions of its action to produce apparent anomalies, and in some instances masked representatives of seemingly extinct races, constituting a reversion to their primitive type. This assumption of new powers is witnessed in the metamorphosis of any insect, and has led to a close scrutiny of life in its earlier or embryonic forms with a view to discover whether all the parts of the imago are present in the earlier period; many students of nature, perceiving the impossibility of effects without something more definite than a name for a cause, have thrown great light upon the subject.

Oken illustrates the gradual elevation in the scale of powers in the articulata by the metamorphosis of the Lepidoptera, which he says are born as worms, represent the crustacea in the pupa stage and finally attain true insect perfection in the imago.

Beginning at the lowest phase of animal perfection as assumed

in the apterous female of Lampyris, we may suppose this to be intermediate between the true larva and a higher form, the winged Coleopteron, of which latter Agassiz says, "they are scarcely more than worms, with certain structures and functions to suit their needs."

These aptera having a latent capability for higher development, in consequence of certain influences, differentiation begins, any apparent change having been preceded by imperceptible ones, such as the gradual concentration of nerves and muscular fibre in the wing-bearing segments. Rudimentary wings and elytra resulting from their fusion under constantly favoring circumstances, attain the maximum of their development in the hardier types of winged Lampyrida. At a certain point we have male and female fireflies as the typically perfect insect.

Once having acquired wings an insect might by prolonged flight change its relations, and may thrive for a while in its new habitat. But either suddenly or by slow process its surroundings are changed. Climatic influences, after a time, test the powers of the winged articulate. Many insects may be presumed to perish, others modify their structures and functions, by non-use of some and development of others. By this course, which must be attended with great loss to individuals, incident to race preservation, some attain a degree of conservative perfection.

In some instances the more robust individuals which are able to contend successfully with the elements, like sturdy gymnasts who develop their muscles by muscular effort, gradually assume a still hardier habit, which is transmitted to their progeny in the larger and more powerful organs of flight, stronger manducatory organs and more fully developed eyes and feet. This evidently progressive phase may be coincident with apparently retrograde metamorphosis in some of the feebler members of the same family. The first tendency to degradation may be preceded by what is termed "an accident," a deformity occasioned by the insect's wings having been mutilated when rudely tossed against resisting objects by the winds. This peculiar feature appears in the offspring as an inherited shortening of the wings, it being well known that peculiarities acquired, or losses sustained, are not only transmissible to the progeny but frequently in an exaggerated form. The transition of an insect from an ærial life to that of an apterous creeper would, if gradual, be coincident with cor

responding alterations in many of its parts in conformity with the new conditions of its existence. In accordance with the laws of adaptive evolution, large eyes, embracing great areas, either in pursuit or avoidance of rapidly-moving objects on the wing, being no longer of use in this degraded position, where they could neither aid the insect's flight nor assist it in procuring sustenance, would gradually be replaced by less globular ones with smaller lenses suited to nearer views. If this degradation were sudden it would be attended with great mortality; hence we find few beetles to be apterous, indicating, in my opinion, one of two probabilities, either that they are unable to sustain the rapidity of the change, or that being a comparatively recent evolution they have not yet attained numerical importance.

According to Mr. Felix Plateau, the centre of gravity differs in the larva and imago of insects, being effected by the coincident enlargement of the thoracic and the diminution of the abdominal segments. This fusion of segments and their ganglia, in view of the part they play in supplying the legs and wings with their suitable nerves of sensation and motion, having adapted the centre of gravity to given conditions, there would be a proper equipoise in all the parts. It can easily be seen that upon a change from the winged to the apterous type, if this were comparatively sudden, the body would be unwieldy, and the disproportion between the parts, rendering the creature's motions heavy, would tend to the non-use of the feet, and the consequent enfeebling of these members. Being unable to travel far in quest of food the insect would from necessity have less opportunity of feeding, thus aborting the manducatory organs from want of use. The chances of individual life being thus diminished the apterous female would no longer exist for herself but, supporting life from material probably stored up in the more active larval stage until she had deposited her eggs in a suitable nidus, would then expire, having completed her mission of race-preservation.

In thus treating of what might be expected from an insect having certain powers of adaptation, I have followed the order as indicated in the different characters seen in Lampyris. I have traced it in its supposed evolution from an apterous to that of an ærial being, and back to earth again as a creeper with heavy disproportioned body, feeble feet and mandibles, small eyes, and brilliant terminal segments.

As illustrating another phase of metamorphosis, I will mention a short-winged male which still retains the larger eyes and more brilliant pigment after they have probably ceased to be of service, pointing to its comparatively recent degradation, and illustrating what Dr. J. LeConte calls " a structure which has outlived its usefulness." The eyes are no doubt retained for awhile by inheritance, but we may safely conclude to be eventually modified.

The preceding remarks have applied only to structures and functions, but at each stage of change in these, corresponding variations have taken place in the coloring of different parts, from black to pale yellow.

In one species the strong-winged male is of a dirty brown, coarsely porous, and finely pubescent on the elytra. The apterous female is a pale buff, glabrous, concolorous; thus, in accordance with the laws appertaining to the different conditions, evolution was arrested in the apterous imago at the color series which belongs to the larva, apparently a simpler process than that which a change of color would imply. This possibility is intimated by Agassiz in his "classification upon embryological data" when he says that the beetle preserves the character of the larva of other insects, assuming only wings and more fully developed legs without reaching other successive metamorphoses. There are lesser stages as represented by the different species, enabling us to link the family in a successive chain from an original pair to this seemingly new creation. This is probably the resultant of an effort at race-preservation, a product of the wear and destruction of individuals into conditions which enable them to perpetuate their race until such time as shall favor their reversion to the original type. The more interesting phenomena of phosphorescence witnessed in this sub-family will be the subject of another article; and it may be proper here to remark, that the researches of the writer, both in the field and the laboratory, have been made, not with a view to fortifying any particular theory, but for the purpose of discovering truth as it is manifested in nature, and applying it to the ever-varying phenomena of insect life.

ONE

ON THE GENEALOGY OF PLANTS.

BY LESTER F. WARD, A. M.

NE of the most remarkable anomalies, which the history of science and that of the human mind affords, is to be found in the appreciation which has been shown of the relationships which the different forms of life present. There has been no lack of acumen in discerning these relationships, in detecting the differences or recognizing the affinities, but there has been frequent failure to comprehend their meaning. The term relationship has been employed in a sort of metaphorical or metaphysical sense, as denoting mere resemblance wholly disconnected from any idea of natural dependence; as if the objects of nature were arbitrarily grouped into classes, orders and genera by the operation of some law of "pre-established harmony." It might be supposed that the term relationship, constantly in use in this sense, ought to have suggested the analogy to family, or consanguineal relationship among men, and led naturalists to seek to account for the resemblances observed among plants and animals on some such principle as that on which family resemblances are explained. Yet this simple deduction proved too profound for the human mind, and botanists and zoologists went on accumulating facts down to the time of Lamarck, and most of them to that of Darwin, without perceiving their most obvious meaning. And there are still many who fail to perceive it, and who openly reject it when pointed out to them.

It is perhaps but proper to add that this state of things has not been wholly due to an inability to make rational deductions, but has been in part brought about by the existence of preconceived ideas which were sufficient to preclude all attempts to reason towards the true conclusion, however plain this course might appear to the unbiased mind.

But now that it is becoming generally recognized that the present forms of life are the true descendants of antecedent forms, and that the observed resemblances are the physical result of real or genetic relationship identical with that which makes children. resemble their parents, it is but natural that old systems of classification should require to be entirely recast and moulded into harmony with this fundamental truth. Such, indeed, is the case, and already marked progress has been made, especially in zoology,