Page:The Scientific Monthly vol. 3.djvu/323

 ORIGIN AND EVOLUTION OF LIFE 317

experiment^ and of what Jennings cautiously terms ^' a conscious aspect of behavior/' In his remarkable studies this author traces the genesis of animal behavior to reaction and trial. Thus the behavior of organ- isms is of such a character as to provide for its own development. Through the principle of the production of varied movements and that of the resolution of one physiological state into another^ anything that is possible is tried and anything that turns out to be advantageous is held and made permanent.* Thus the sub-psychic stages when they evolve into the higher stages give us the rudiments of discrimination, of choice, of attention, of desire for food, of sensitiveness to pain, and alflo give us the foundation of the psychic properties of habit, of memory and of consciousness.^^ These profound and extremely ancient powers of animal life exert a constant creative influence on animal form, whether we adopt the Lamarckian or Darwinian explanation of the origin of animal form, or find elements of truth in both explana- tions.^^ Less cautious observers than Jennings^* find in the Foraminif- era the rudiments of the highest functions and the most intelligent behavior of which undifferentiated protoplasm has been found capable.

In the evolution of the Protozoa^* the starting point is a simple cell consisting of a small mass of protoplasm containing a nucleus. This passes into the plasmodial condition of the Bhizopods, in which the protoplasm increases enormously to form the relatively large, unpro- tected masses adapted to the creeping or semi-terrestrial mode of life. From these evolve the forms specialized for the floating pelagic habit, namely, the Foraminifera and Radiolaria, protected by an excessive de- velopment and elaboration of their skeletal structures.^* In the Masti- gophora the body develops flagellate organs of locomotion and food- capture. As an offshoot from the ancestors of these forms arose the Giliata, the most highly organized unicellular types of living beings, for a Ciliate like every other protozoan is a complete and independent organism and is specialized for each and all of the vital functions per- formed by the higher multicellular organisms as a whole.

In the chemical life of the Protozoa*** (Amoeba) the protoplasm is made up of colloidal and of crystalloidal substances of different density, between which there is a constant, orderly, chemical activity. The relative speed of these orderly processes is due to specific catalyzers which control each successive step in the long chain of chemical actions. Thus in the breaking down process (destructive metabolism) the by-

» Jennings, H. S., 1906, pp. 318, 319.

10 Op, cit., pp. 82^-335.

11 These rival theories are fully explained below in the introduction to the. second lecture.

12 Heron-AUen, Edward, 1915, p. 270. i« Minchin, E. A., 1916, p. 277.

1* Op, dt,, p. 278.

18 Calkins, Gary N., 1916, p. 260.

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