Scientists declare that they are now able to trace the development of the two diverging lines of sex-demarcation from the time of their separation, or from the time when these principles were confined within one and the same individual. In order to understand the origin of sex, it becomes necessary to recall, briefly, the theory of the development of life on the earth as set forth by the savants.
As science deals only with matter, a mechanical theory of the universe is inevitable. As science is wholly materialistic, it is perfectly consistent in its declaration that the senses and the intellect constitute the only means whereby truth may be discovered. Modern philosophy, on the other hand, which deals less with matter itself than with the causes which underlie the development of matter, affirms that a character has been developed in human beings which in its capacity to discern truth, far transcends the intellect. That character is intuition. But as we are dealing only with scientific observations, philosophical speculations do not here concern us.
The fundamental idea, which must necessarily lie at the bottom of all natural theories of development, is that of a gradual development of all (even the most perfect) organisms out of a single, or out of a very few, quite simple, and quite imperfect original beings, which came into existence, not by supernatural creation, but by spontaneous generation.[1]
According to the theory of evolution as elaborated by scientists, the history of man begins with small animated particles, or Monera, which appeared in the primeval sea. These marine specks were albuminous compounds of carbon, generated by the sun’s heat, which made their appearance as soon as the mists which enveloped the earth were sufficiently cleared away to permit the rays of the sun to penetrate them and reach the surface of the globe. Concerning the origin of the principle of life which these particles contained, or regarding the development of organic bodies from inorganic substances, the more timid among naturalists declare that in the present state of human knowledge it is impossible to know anything, while others of them, more bold, or more confident of the latent powers of the human intellect, after having elaborated a natural or mechanical explanation for the development of all organic forms, are not disposed to accept a supernatural theory for the beginning of life. For example, since organic structures represent the development of matter according to laws governing the chemical, molecular, and physical forces inherent in it, it is believed that the gulf separating organic and inorganic substances is not so difficult to span as has hitherto been supposed. Among those who hold this view may be ranked the celebrated naturalist, Ernst Haeckel.
Regarding the phenomena of life this writer observes: “We can demonstrate the infinitely manifold and complicated physical and chemical properties of the albuminous bodies to be the real cause of organic or vital phenomena.”[2] Indeed, in whatever manner the vital force within them originated, naturalists agree that from these particles have been derived all the forms, both animal and vegetable, which have ever existed upon the earth.
As speculations concerning the origin of matter lie without the domain of natural or scientific inquiry, they form no part of the investigations of the naturalist. So far as is known, matter is eternal, and all that may be learned concerning it must be gleaned by observing the changes, chemical and molecular, through which it is manifested. By those who have observed the laws which govern the manifold changes in matter, the fact is declared that the various manifestations in form and substance constitute the only creation of which we may have any knowledge; and, moreover, that the genesis of existence is going on as actively in our time as at any previous period in the history of matter. So far as human knowledge extends, no particle of matter has ever been created and none ever destroyed. This continuous process of transmutation of substance and change of form, in other words the phenomena designated Life, may have been in operation during all the past, and may continue forever.
As all speculations concerning the origin of matter have been unavailing, so all attempts to solve the problem of the origin of life have proved futile. The experiments recently carried on in the Rockefeller Institute, in which by means of chemical processes detached organs from the bodies of animals have been made to perform their normal functions, are interesting and instructive, but these experiments furnish no clue to the origin of the force which animates living organic matter. Why the nucleated cells which we call a heart should pulsate whilst those which we call a liver should secrete bile, nobody knows.
That all life on the earth has been derived from one, or at most from a few original forms, is said to be proved by ontogeny, or the history of the germ, which in its development passes through a number of the forms which mark the ascending scale of life.
Through the study of comparative anatomy, the fact has been discovered that the individuals composing the various orders of the great vertebrate series are all moulded “on the same general plan”; that up to a certain stage in the development of the several germs—for instance those of the man, the ape, the horse, the dog, etc.,—they are not distinguishable the one from the other, and that it is only at a later stage of development that they take on the peculiarities belonging to their own special kind. The number and variety of forms which appear in the animal and vegetable world make it difficult to conceive of the idea that all have sprung from one, or at most from a few original types, yet the chain of evidence in support of this theory seems quite complete.
Natural Selection, by which it is demonstrated that organized matter must move forward simply through the chemical and physical forces inherent in it, furnishes a key to all the phenomena of life, both animal and vegetable, which have ever appeared on the earth. Natural Selection, we are told, depends for its operation on the interaction of two processes or agencies, namely, Inheritance and Adaptation. Through Inheritance germs receive from their parents a plastic form which, as all development is a function of external physical conditions, is itself nothing more than a “manifestation of the remains of antecedent physical impressions.” This inherited form causes them to go forward in a predestined course, while through Adaptation there is a constant tendency to change that predestined form imposed upon them by their parents to one better suited to their changing physical conditions.