If we compare once more the facts of histological synchromatism of Hippolyte with the facts of accidental or instinctive synchromatism of Maja, we shall see that the essentials of the two phenomena are identical, and that they consist in a chromo-kinetic resonance in response to the luminous agents of the environment.

This resonance, by the medium of the retino-neural channel, is manifested in Hippolyte by the kinetic phenomena of the chromatophores, while, in the Maja, it is interpreted by the chromo-kinetic phenomena of the entire animal, that is to say, by the chromotropic movements which necessarily determine the corresponding conceal

ment.

This is all that I have to say in regard to the experimental analysis of the instinct which leads the Brachyura Oxyrhyncha to disguise themselves. There remains only to recapitulate the results.

X. GENERAL CONCLUSION: THE PHYSIOLOGICAL DETERMINISM OF THE INSTINCT OF SELF-CONCEALMENT IN ITS ENSEMBLE.

I feel obliged to speak only of physiological determinism, exclusive of any psychological tendency. The reason is, that it is absolutely impossible for us to know anything whatever respecting the psychic state of the lower animals, to which one can not even apply reasoning by analogy with our introspective states. Thus, the question of "choice," either conscious and voluntary, or determined by "sensations" of color, sensations "agreeable" in certain conditions and "disagreeable " in others, this question may be very interesting, but it does not exist for us as a scientific question; all the more as everything takes place with our animals as if psychic states did not exist, these states having no influence over the course of the instinctive reactions that we have just described and analyzed.

a

Now, neither from the gnoseological point of view, nor from the methodological point of view, have we committed an error in limiting ourselves in this study to the objective method: Physiological (experimental) and biological (comparative).

Here is the general result:

The instinct of the Maja in all its curious complexity is composed of two parts, the second of which, the one which constitutes the fundamental part of instinct, can be separated and studied by itself. This simplification of instinct is shown in the case of the resection of the cerebral mass containing the photo-receptive ganglia or of the removal of the peripheral organs of photo-reception.

a The fundamental statement of my gnoseological and methodological conceptions in zoopsychology will be found in the first part of my complete work in the Revue Polonaise de Philosophie (Przeglad filozoficzny), vol. 10, fasc. 3, Warsaw, 1907.

In instinct not maimed, the first phase is that of the chromoreactions of the animal in regard to the color of the environment and the colored surfaces of the objects of concealment. The material for disguising is determined by the variable synchromatic chromotropism, which drives the animal inevitably toward certain colored surfaces, according to the sum of the given conditions. Once the animal touches the material, whatever it may be, if nothing prevents it, there begins immediately the long series of very complicated reflex movements provoked by the tangoperceptions of the claws, directed by the tango- and chemoperceptions of the buccal pieces, and helped on toward the end by the tangoperceptions of the dorsal hooks.

a Tactile perceptions.

THE ORIGIN AND DEVELOPMENT OF PARASITICAL

HABITS IN THE CUCULIDE.

[With 2 plates.]

By C. L. BARRETT, Melbourne.

For nearly two thousand years certain remarkable habits of the family Cuculidæ have exercised the minds of naturalists and philosophers. The origin of these habits has remained hidden behind an impenetrable veil of mystery, which is only now being slowly and patiently lifted by means of the observations and researches of a number of ornithologists in different parts of the world. The first actual record which has come to us out of the past of the unusual ways of these strange birds is contained in a scientific treatise written by one Aèlian, a Latin author, who flourished during the second century. In this ancient monograph it is stated that the cuckoo always lays her eggs in the nests of other birds, being too indolent to undertake the care of her own offspring.

We do not find many other important references to the cuckoo until the time of Gilbert White, the famous old naturalist-parson of Selborne, whose charming series of letters on the wild life in his Hampshire home, known to us as "The Natural History of Selborne," are full of interest still. White mentions that the European cuckoo (C. canorus) is a summer migrant, appearing in his garden. early in the month of April each year, and the whole of one letter, dated from Selborne, February 19, 1770, is devoted to a consideration of the habits of the mysterious stranger.

Daines Barrington, a wealthy and aristocratic young naturalist, had written to the Reverend Mr. White, asserting that the cuckoo did not deposit her egg indiscriminately in the first nest she came across, but, on the contrary, searched out the home of a bird whose natural food was to some extent similar to her own and therefore a desirable foster parent for the prospective baby cuckoo. White, in reply, said that the idea was quite new to him, and that, after giving much thought to the subject, he had come to the conclusion that the

a Reprinted by permission of The Emu, Melbourne, vol. 6, 1906-7, pp. 55-60. 45745°- -SM 1909- -32

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hypothesis was reasonable enough, as, personally, he could not remember ever having witnessed a young cuckoo being tended by any but soft-billed insectivorous birds. He adds, very quaintly, that the depositing of its eggs by the cuckoo in another bird's nest is such a monstrous outrage on maternal affection that, had it been related of a bird in the Brazils or Peru, it would not have merited belief. On October 8, 1770, the observant old naturalist again writes, this time from Ringmer, in Sussex, to the effect that he has just seen a young cuckoo in a lark's nest, and that it was very pugnacious, pursuing his finger and buffeting and sparring with its wings like a game cock. I have often noticed this bad-tempered disposition myself amongst our Victorian species, and it seems to be quite in accordance with the general nature of the birds as a class.

Coming to more recent time, we find Charles Darwin, in his chapter on instinct in the "Origin of Species," throwing the searchlight of his genius into the dark corners of the cuckoo problem. Variation and natural selection, the great naturalist considers, have undoubtedly been the main factors in building up the parasitical instinct which we see working in all its horrible perfection to-day. Let it be supposed, for instance, that an early progenitor of our lovely little shining bronze cuckoo (Chalcococcyx plagosus) occasionally departed from the natural order of things, and deposited one of her tiny eggs in the nest of some other species of bird, either accidentally or by reason of being compelled to lay before her own nest was completed, just as to-day we frequently find the pale blue eggs of starlings and mynahs scattered about the open fields or on our suburban lawns. If we conceive further that the egg thus consigned to its fate in an alien nest has duly brought forth a baby cuckoo, which, being reared by the foster-parents, has unconsciously acquired, during the nestling period, a predilection for the company of its foster-parents and their kind, is it not probable that this particular cuckoo would, if a female, sometimes deposit an egg in the nest of a bird belonging to the species amongst whom her infancy was passed? The cuckoo would also naturally transmit this predilection to her own offspring, and they in turn would rear young, or leave them to be reared by foster-parents, endowed with the same inclination toward parasitism. As time went on, and successive generations of cuckoos from the same parent stock had been born and died, the parasitical instinct would gradually become more pronounced in the family, and, being an aid to its preservation and perpetuation, would finally become a fixed, immutable instinct.

As a proof of this theory I may cite the peculiar habits of certain species of the American Icteridae or cowbirds (Molothrus), which, according to Mr. W. H. Hudson, author of "The Naturalist in La