have observed a few species of plants and animals which deviate from the general rule of constancy in present systematic species, and exhibit qualitative mutations with constant results.

Let us give the principal outlines of the arguments of de Vries and Wasmann.

1. In the year 1886 de Vries observed a plant called Oenothera Lamarckiana, of American origin and possessing great powers of fertility. At once he conceived the idea that precisely this fertility might possibly inaugurate a period of mutation, if the plant were put into foreign soil. Two deviating forms were discovered on the same field with the Oenothera Lamarckiana. They manifested the constancy of true species, but were unknown to the systematists of the day. This discovery rendered de Vries' supposition highly plausible. Encouraged and confirmed in his belief de Vries took nine well developed specimens of the Oenothera Lamarckiana and transplanted them from Hilversum, a town situated between Amsterdam and Utrecht, to his garden in Amsterdam. And what was the result? Within seven generations he produced from these nine single specimens about 50,000 plants and among their number about 800 specimens that had unmistakably deviated from the original type. This interesting and marvellous result is more clearly expressed in the figures of the following table: (1)

GENETIC TREE of EnoTHERA LAMARCKIANA.
(The numbers designate individuals.)

It is understood that all specimens were derived from the Enothera Lamarckiana in all generations enumerated.

(1) Biologisches Centralbl., XXI., D. 298.

Scin

tillans.

Now the various forms of mutation enumerated in the table are by no means variations or races commonly so-called, but exhibit and possess all the characteristic traits of systematic species.

For, (1) the newly originated forms differ from their parentstock not merely in a few details, as variations generally do, but in all parts and in all stages of development as well.

(2) The new forms are not connected with each other by means of transitional forms. They can be recognized already as young plants, but are, of course, more readily distinguished by the points of difference coming into prominence as the plants approach their full-grown state. Furthermore, transitional forms that might give rise to doubts concerning the species to which they belong, are hardly ever to be found. So true is this that the systematic position of dead and dried specimens can promptly be determined to

exactness.

(3) The new forms, moreover, possess perfect constancy and transmit the features peculiar to their nature unchanged to their offspring. Nor is any sign of an atavistic return to the Lamarckiana type to be noticed. Thus, to mention only one example, the 450 seeds produced by the one specimen of the Oenothera gigas in 1895 were sown in 1897, and sent forth 450 specimens of the 0. gigas, whilst only one of them betrayed at the same time some characteristics of the O. nanella and not a single one those of the O. Lamarckiana.

Consequently it appears to be highly probable that the O. Lamarckiana has in fact produced a number of true systematic species. It is, moreover, plain that only an intrinsic principle can fully account for the sudden and saltatory changes wrought in the evolutionary process we have just described.

II. More intricate and in many ways different is the argument advanced by Wasmann, which we shall now proceed to consider at least in its broadest outlines. It is a well-known fact that in the nests of certain ants a number of insects, called guests, are wont to dwell, and as the case may be maintain a more or less friendly (mutual) or indifferent relation to the ants themselves. These insects, in the main, are members of the beetle order and belong especially to the family of the Staphilinida or rove-beetles. Remembering this simple fact we shall be enabled more easily to understand the statement that follows representing the "major" of Wasmann's argument.

Protracted observations and many experiments showed that the four ant guests: Dinarda dentata Grav., D. Maerkelii Ksw., D. Hagensi Wasm., and D. pygmaea Wasm, were seen to manifest themselves as four different forms of adaptation (Anpassungsformen) of one and the same generic type to the four different species of ants in whose nests they dwelt (to the four ants: Formica sanguinea Latr., F. rufa L., F. exsecta Nyl., and F. fusca-rufibarbis For.). The adaptation refers primarily to size and color. Its purpose is to protect the Dinarda, which belongs to the so-called indifferent guests.

Now these various adaptations of one and the same generic type clearly point to the actual differentiation of the type with results of a lasting nature,-in other words to a real specific evolution.

For, as comparative zoogeography attests, the deviation of the four forms from the original type of the Dinarda and their specific development has not yet reached the stage of completion, but only different stations of perfection.

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1. The progress in specific development to which the four forms of the Dinarda are subject, is greatest in those parts of the European continent, where the final retreat of ice and ocean in the last glacial period was first accomplished, as in the northern valley of the Rhine, in lower Austria, Silesia, Bohemia, etc. 'It was near Linz on the Rhine, says Wasmann, that I observed a great number of the four forms of the Dinarda together with their respective hosts. But all of them clearly revealed the characteristics of well-defined species. No transitional forms could be discovered; the points of difference between the four were unvarying." (1)

2. The progress is least in those tracts that were longest buried under ice and water, as it happened to the Central Alps and the regions along the northern and north-western coasts of middle. Europe. Here the differentiation has scarcely begun.

3. Between these two extremities a wide region of transition intervenes where the differentiation of the generic type of the Dinarda is still in a state of progressive development. Though this latter statement, as restricted by Wasmann himself, is still somewhat hypothetical in its generalization, still the fact remains that especially the Dinarda pygmaea offers a striking example of specific evolution going on before our very eyes. By way of varieties and races it has attained different stations of perfection at different points of its geographical distribution.

(1) Biologisches Centralbl., XXI., p. 703.

The factors that were and are still active in this evolution are, next of all, an intrinsic principle of development acting in harmony with an external directive which, in the case under consideration, can easily be detected in the difference of the ants that harbor the Dinardas in their nests.

Moreover, by the same process of evolution, we can easily explain the differentiation within the systematic genus to which they belong. For no other agents are required for this generic differentiation, than those that actually account in our own day for the development of the Dinarda pygmaea.

The objection that the four Dinarda are not to be regarded as four different species, does not weaken the force of our argument. For. granted they be only races, they are by no means equivalent races, but such as have reached different stations on the way of specific development and differentiation.

Consequently, far from being surprised, we find it very reasonable, that at the end of his learned treatise and substantial explanation, Wasmann comes to the conclusion: "If one could prove that all these facts (Wasmann mentions many more, the argumentative value of which is of an indirect character) can be accounted for equally well or even better without accepting the theory of evolution, then I admit that this theory in the present case at least is not sufficiently upheld by facts. If not, no one can blame me, for acknowledging that theory as the best explanation of facts otherwise inexplicable." (1)

These are the arguments proposed by Hugo de Vries and E. Wasmann. What are we to think of them? They evidently deny the absolute constancy of specific characters and maintain that the idea of a saltatory evolution proceeding from an intrinsic principle and under the guidance of an external directive is no longer a mere hypothesis, but a fact supported by direct arguments of considerable weight and probability. How far this probability goes, is difficult to state. As far as Wasmann's argument, at least, is concerned. an unusual and very minute knowledge of the structure and habits of tiny insects is required for the full appreciation of the facts.

This much, however, is certain that no one can object to the arguments of the two scientists on the ground of religion or philosophy, unless he mistakes the meaning of evolution, nor on the ground of the natural sciences, unless he is able to disprove the facts or to show that the acceptance of evolution is unnecessary to understand and explain them.

(1) Biol. Centralbl., XXI., p. 750.

H. MUCKERMANN, S.J.

A QUESTION OF TIME.

(Concluded.)

III.

MR. MAITLAND had rallied surprisingly. Every day for a fortnight a generous supply of milk and provisions had been delivered at the cottage, and with the nourishment and stimulant which he had so greatly needed he seemed to receive a new lease of life and energy. His doctor was greatly pleased with the improvement; he had met Father Louis in the lane, on the day of the priest's first visit to Redland Cottage, and they had had a long consultation about the

case.

"I will give you a free hand with him, Father," the Doctor had said after their professional talk, "and I am only too thankful to have your co-operation; he has been a real anxiety to me, for he has been half starved when he should have been having the most abundant nourishment and unlimited stimulants, and as he is as proud as Lucifer, I have not seen my way to helping him at all. I am surprised that you have been able to do so much with him; or rather I should say, now I have had the pleasure of meeting you, Father, that I am not surprised; but it is a wonder he consented to see you, for he is a red-hot agnostic, and he seemed to me to be perfectly fanatical in his hatred of clergymen. I suggested one day that he should see the vicar-it has really been a case for charitable relief, you know—and he looked like murdering me there and then."

"He did not exactly receive me with rapture," said Father Louis, dryly, "but I am not very easily scared away, and I mean to do all I can for him for the sake of the children."

Ah, yes; poor little souls," said the Doctor, thoughtfully. "Well, you may be able to save him, in the bodily sense, there is a chance for him, if you can get that old wine into him you were speaking about, but as for his soul"-the Doctor gathered up his horse's reins. and put his foot in the stirrup; then as he settled himself on his saddle he added rather mischievously, "that would be a very bright jewel in your crown, Father," and they both laughed, as they said good-bye with great friendliness.

It had been a trying fortnight for Father Louis, and although he

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