According to the now almost universally (that is, among educated scientific people) accepted theory of Evolution, each living being upon this earth is a result of a very slow process of development, which commenced with a low form of life many millions of years ago, and has since been operating continuously, becoming more and more complex, and imperceptibly attaining greater perfection as each fresh stage was accomplished. From the homogeneous to the heterogeneous, from inorganic to organic, from Amoeba to man, the evolutionary development has slowly, steadily, and surely advanced step by step, in obedience to certain well-defined laws. Yet it is impossible to discern in this slow process of evolution any well-marked difference between one particular species and the next of kin, although the difference becomes clearly apparent if we take two species separated from each other by considerable time; just as it is impossible to detect any alteration in form and feature between a child of six days old and the same child of seven days old, while the change is very evident after the lapse of several weeks or months. If we were to photograph a human being regularly each day from the moment of its birth to the time of its decease at the age of eighty, we should be unable to detect any real difference between the portraits on any two consecutive days; but the difference between the child of a week old and the young man of twenty years would be enormous, as would be that between the full-grown youth and the tottering old man. As the human individual in its earliest condition of existence is not possessed of the same faculties as it afterwards enjoys as a more perfect development, so, in like manner, the species in its primal condition was wanting in the loftier qualities now possessed by the higher animals, such as consciousness, sight, hearing, taste, smell, and touch, all of which have been gradually evolved as the various life-forms developed from lower and more simple to higher and more complex kind. For instance, at a very early period of man’s individual existence he possessed no brain, eyes, ears, mouth, or nose, and, therefore, was quite incapable of mentating, seeing, hearing, tasting, or smelling; but, as the organism very gradually developed into a higher and more complex kind, these various organs manifested themselves, and slowly arrived at such perfection as we find in the human infant at birth. Precisely so was it with the race. The lowly Moneron was of homogeneous structure, possessing neither parts nor kind, but gradually differentiating into nucleus and cell; its descendants, the Gastroeada, becoming possessed, by a process of invagination, of an external layer of nucleated cells and an internal and more delicate layer, thus forming a hollow organism, or Gastrula. This external cellular integument was the original sense-organ of the animal kingdom, from which developed the organs of special sense. Though without nerve and special sense-organs, yet these little hollow Gastroeada, and, in fact, their ancestors, the AmoebÆ, which consisted of simple protoplasmic cells, each enclosing a nucleus, were possessed with sensory perception, being influenced by light, and by variations of pressure and temperature. As the evolutionary process continued, and the animal kingdom assumed higher forms, the original epidermal general sense-organ became converted into several special organs of sense, each specialisation commencing with a simple depression upon the integument of the organism; numerous little epidermal nerves of perception were formed, which could perceive changes of pressure and of temperature, and some of which gradually became enabled to understand particular influences affecting them, such as those produced by a strong odour, light-waves, and sound-waves. By adaptation, the extremities of these sense-nerves became expanded and enlarged, so as to enable them the better to understand the particular influences; and this expansion was accompanied by a corresponding depression on the integument, which cup-like formation afterwards became converted into an eye, or other organ of special sense, very imperfect in the invertebrate forms of life, imperfect in the fish, more perfect in the amphibian, and still more perfect in the mammal forms, such as apes and men. In short, the life-history of the individual is an exact counterpart in miniature of the life-history of the species up to the particular point reached by the particular individual.

The order and mode of development is precisely the same in all animal organisms, and may be conveniently studied by placing a hen’s egg in an incubating machine, and carefully watching it for the space of three weeks. It will be observed that the eye, ear, nose, and mouth are not present at the commencement of the process, but make their appearance later on, about the third or fourth day of incubation, as tiny depressions on the integument, from which condition they gradually develop into perfect organs of special sense, as possessed by the full-grown chicken; the eyes, which receive the impressions caused by light-waves; the ears, which receive those made by sound-waves; the nose, by which odours are discerned; the mouth, which holds the taste-organ; and the skin, which remains the organ of touch and perception of temperature. Now, when we consider for a moment these wonderful phenomena, we cannot help being struck by the remarkable manner in which the animal kingdom has been slowly and steadily progressing towards perfection, in spite of the enormous physical difficulties encountered; and we cannot help coming to the conclusion that, inasmuch as there was once a time when no animal existed having eyes, ears, nose, or mouth, and, still later, a period when these special sense-organs existed in a very imperfect condition, it is highly probable that in the future ages man, who now possesses special senses of a high order, will acquire even still more highly-developed faculties.

In congratulating ourselves upon the advance made by our own particular species over other members of the animal kingdom, we must never forget that, although we can mentate, see, hear, smell, taste, and feel, while myriads of our lowly brethren can do none of these, we yet are incapable of solving the mighty problems of the universe with any or all of these organs without artificial aid. No man on earth has ever yet been able to solve the mighty problem of existence, in spite of his great intellectual powers. No man has ever yet been able to see a millionth part of the wonders in the heavens above, or in the earth beneath, with his own unaided eye; but with the telescope and microscope new worlds have been opened out to him. We are as yet, undoubtedly, in but a transitory condition, the victims of an imperfect organisation, subject to a partially-developed brain and nervous system, and to five imperfect special senses. We must accept the situation philosophically, and without grumbling, and do our best to make good use of the senses we have, and leave the solution of problems we are unable to solve to future races of men, who will be possessed of better materials with which to operate.

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