On the Genesis of Species

by St. George Jackson Mivart

Mr. Darwin appears, by "Natural Selection," to destroy the reality of species, and by Pangenesis that of the individual. Mr. Lewes observes[^[227]] of the individual that "This whole is only a subjective conception which summarizes the parts, and that in

point of fact it is the parts which are reproduced." But the parts are also, from the same point of view, merely subjective until we come to the absolute organic atoms. These atoms, on the other hand, are utterly invisible, intangible; indeed, in the words of Mr. Darwin, inconceivable. Thus, then, it results from the theories in question, that the organic world is reduced to utter unreality as regards all that can be perceived by the senses or distinctly imagined by the mind; while the only reality consists of the invisible, the insensible, the inconceivable; in other words, nothing is known that really is, and only the nonexistent can be known. A somewhat paradoxical outcome of the speculations of those who profess to rely exclusively on the testimony of sense. "Les extrêmes se touchent," and extreme sensationalism shakes hands with the "das seyn ist das nichts" of Hegel.

Altogether the hypothesis of Pangenesis seems to be little, if at all, superior to anterior hypotheses of a more or less similar nature.

Apart from the atoms of Democritus, and apart also from the speculations of mediæval writers, the molecules of Bonnet and of Buffon almost anticipated the hypothesis of Pangenesis. According to the last-named author,[^[228]] organic particles from every part of the body assemble in the sexual secretions, and by their union build up the embryo, each particle taking its due place, and occupying in the offspring a similar position to that which it occupied in the parents. In 1849 Professor Owen, in his treatise on "Parthenogenesis," put forward another conception. According to this, the cells resulting from the subdivision of the germ-cell preserve their developmental force, unless employed in building up definite organic structures. In certain creatures, and in certain parts of other creatures, germ-cells unused are stored

up, and by their agency lost limbs and other mutilations are repaired. Such unused products of the germ-cell are also supposed to become located in the generative products.

According to Mr. Herbert Spencer, in his "Principles of Biology," each living organism consists of certain so-called "physiological units." Each of these units has an innate power and capacity, by which it tends to build up and reproduce the entire organism of which it forms a part, unless in the meantime its force is exhausted by its taking part in the production of some distinct and definite tissue—a condition somewhat similar to that conceived by Professor Owen.

Now, at first sight, Mr. Darwin's atomic theory appears to be more simple than any of the others. It has been objected that while Mr. Spencer's theory requires the assumption of an innate power and tendency in each physiological unit, Mr. Darwin's, on the other hand, requires nothing of the kind, but explains the evolution of each individual by purely mechanical conceptions. In fact, however, it is not so. Each gemmule, according to Mr. Darwin, is really the seat of powers, elective affinities, and special tendencies as marked and mysterious as those possessed by the physiological unit of Mr. Spencer, with the single exception that the former has no tendency to build up the whole living, complex organism of which it forms a part. Some may think this an important distinction, but it can hardly be so, for Mr. Darwin considers that his gemmule has the innate power and tendency to build up and transform itself into the whole living, complex cell of which it forms a part; and the one tendency is, in principle, fully as difficult to understand, fully as mysterious, as is the other. The difference is but one of degree, not of kind. Moreover, the one mystery in the case of the "physiological unit" explains all, while with regard to the gemmule, as we have seen, it has to be supplemented by other powers and tendencies, each distinct, and each in itself inexplicable and profoundly mysterious.

That there should be physiological units possessed of the power attributed to them, harmonizes with what has recently been put forward by Dr. H. Charlton Bastian; who maintains that under fit conditions the simplest organisms develop themselves into relatively large and complex ones. This is not supposed by him to be due to any inheritance of ancestral gemmules, but to direct growth and transformation of the most minute and the simplest organisms, which themselves, by all reason and analogy, owe their existence to immediate transformation from the inorganic world.

Thus, then, there are grave difficulties in the way of the reception of the hypothesis of Pangenesis, which moreover, if established, would leave the evolution of individual organisms, when thoroughly analysed, little if at all less mysterious or really explicable than it is at present.