The Wonders of Life: A Popular Study of Biological Philosophy

by Ernst Haeckel

The great importance of electricity as an agency in nature, both organic and inorganic, has only lately been fully appreciated. Electric changes are connected with many (if not, as is now supposed, with all) chemical and optical processes. Man himself and most of the higher animals have no electric organs (apart from the eye), and no sense-organs that experience a specific electric sensation. It is probably otherwise with many of the lower animals, especially those that develop free electricity, such as the electric fishes. The larvæ of frogs and embryos of fishes, if put in a vessel of water through which a galvanic current is sent, place themselves when it is closed with their longitudinal axis in the direction of the current, with the head directed to the anode and the tail to the cathode (Hermann). Again, the luminous sea-animals which cause the beautiful phenomenon of the illumination of the sea, and the glow-worms and other luminous organisms, have probably an unconscious feeling of the flow of electric energy associated with these phenomena. Many plants show a direct reaction to electric stimuli; when, for instance, we send a constant galvanic current for some time through the points of their roots (very sensitive organs, compared by Darwin to the brain of the animal), they bend towards the cathode.

Many of the protists are very sensitive to electric currents, as Max Verworn especially proved by a series of beautiful experiments. Most of the ciliated infusoria and many of the rhizopods (amœba) are cathodically sensitive or negatively galvanotactic. When we send a constant electric current through a drop of water in which thousands of paramœcium are moving about, all the infusoria swim at once, with the anterior pole of the body foremost, towards the cathode or negative pole; they accumulate about it in great crowds. If the direction of the current is now changed, the whole swarm at once make in the opposite direction for the new cathode. Most of the flagellate infusoria do just the reverse; they are anodically sensitive or positively galvanotactic. In a drop of water, in which swarms of polytoma are moving about, all the cells swim at once towards the anode or positive pole, when an electric current is sent through. The opposite galvanotropic behavior of these two groups of infusoria in a drop of water, in which they are mixed together, is very interesting; as soon as a constant stream enters it, the ciliata fly to the cathode and the flagellata to the anode. When the current is reversed the two swarms rush at each other like hostile armies, cross in the middle of the drop, and gather at the opposite poles. These and other phenomena of galvanic sensation show clearly that the living plasm is subject to the same physical laws as the water that is decomposed into hydrogen and oxygen by an electric current. Both elements feel the opposite electricities.

SCALE OF SENSATION AND IRRITABILITY

1st	Stage Sensation of Atoms. Affinity of the elements in every chemical combination.
2d	Stage Sensation of Molecules (groups of atoms): in the attraction and repulsion of molecules (positive and negative electricity, etc.).
3d	Stage: Sensation of Plastidules (micella, biogens, or plasma-molecules): in the simplest vital process of the monera (chromacea and bacteria).
4th	Stage: Sensation of Cells: irritability of the unicellular protists (protophyta and protozoa): erotic chemotropism connected with the nucleus and trophic with the cell-body.
5th	Stage: Sensation of Cœnobia (volvox, magosphæra). With the formation of cell-communities we have association of sensations (individual feeling on the part of the social cells together with common feeling on the part of the community).
6th	Stage: Sensation of the Lower Plants. In the metaphyta or tissue-plants all the cells are still equally sensitive at the lower stages: there are no special sense-organs.
7th	Stage: Sensation of the Higher Plants. In the higher metaphyta specially sensitive cells, or groups of cells, with a specific energy, are developed at certain points: sense-organs.
8th	Stage: Sensation of the Lower Metazoa, without differentiated nerves or sense-organs. Lower cœlenteria: sponges, polyps, platodaria.
9th	Stage: Sensation of the Higher Metazoa, with differentiated nerves and sense-organs, but still without consciousness(?). The higher cœlenteria and most of the cœlomaria.
10th	Stage: Sensation with Dawning Consciousness, with independent formation of the phronema. The higher articulata (spiders and insects) and vertebrates (amphibia, lower reptiles, lower mammals).
11th	Stage: Sensation with Consciousness and Thought: amniotes: higher reptiles, birds, and mammals: savages.
12th	Stage: Sensation with Productive Mental Action in Art and Science: civilized men.

XIV

MENTAL LIFE

Mind and soul—Intelligence and reason—Pure reason—Kant's dualism—Anthropology—Anthropogeny—Embryology of the mind—Mind of the embryo—The canonical mind—Legal rights of the embryo—Phylogeny of the mind—Paleontology of the mind—Psyche and phronema—Mental energy—Diseases of the mind—Mental powers—Conscious and unconscious mental life—Monistic and dualistic theory—Mental life of the mammals, of savages, and of civilized and educated people.

The greatest and most commanding of all the wonders of life is unquestionably the mind of man. That function of the human organism, to which we give the name of "mind," is not only the chief source of all the higher enjoyment of life for ourselves, but it is also the power that most effectually separates man from the brute according to conventional beliefs. Hence it is supremely important for our biological philosophy to devote a few careful pages to the study of its nature, its origin and development, and its relation to the body.

At the very outset of our psychological inquiry we are met by the difficulty of giving a clear definition of "mind," and distinguishing it from "soul." Both ideas are extremely ambiguous: their content and connotation are described in the most various ways by the representatives of science. Generally speaking, we mean by mind that part of the life of the soul which is connected with consciousness and thought, and is, therefore, only found in the higher animals which have intelligence and reason. In a narrower sense reason is regarded as the proper function of mind, and as the essential prerogative of man in the animal world. In this sense Kant especially has done much to strengthen the prevailing conception of mental action, and has, by his Critique of Pure Reason, converted philosophy into a mere "science of reason." In consequence of this conception, which still prevails widely in scientific circles, we will first study the mental life in the action of reason, and try to form a clear idea of this great wonder of life.