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The earliest ancestors of our race were simple Protophyta, and from these our protozoic ancestors were developed afterwards. From the morphological point of view both the vegetal and the animal Protists were simple organisms, individualities of the first order, or plastids.
We may call it the Blastaea. Its body consisted, when fully formed, of a simple hollow ball, filled with fluid or structureless jelly, with a wall composed of a single stratum of ciliated cells. There were probably many genera and species of these blastaeads in the Laurentian period, forming a special class of marine protists.
But they all grow from the same roots among the primitive forms of life. Unicellulars these must have been, but not like our “Protists.” They should be thought of as primitive forms having within themselves the potentialities of the most diverse and widely separate evolution-series to which they gave rise, as it were, along diverging fan-like rays.
First, they attempt to interpret the expressions of will, feeling and need, the spontaneous activities and movements of the lowest forms of life—protists—as “pure reflexes,” as processes which take place in obedience to stimuli, and thus are ultimately due to chemical and physical influences and causes without the intervention of a psychical motive; and, secondly, when this has been apparently or really achieved, the theory of irritability and reflex mechanism is pushed from below upwards, until even the most intricate and complex movements and operations of our own body, which we have wrongly distinguished as acts or behaviour from mere processes of stimulation, are finally recognised as reflexes and liberations due to stimuli.
It is obvious, and it is also thoroughly justifiable, that all attempts along these lines of interpretation should be undertaken in the first place in connection with the simplest and lowest forms of life. It is in the investigation of the “Protists,” the study of the vital phenomena of the microscopically minute unicellular organisms, that attempts of this kind have been most frequently made.
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