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Updated: May 2, 2025
They are minute bodies, most of which are made individually visible only by the microscope. All of them are extremely simple in structure, and some of them, as the Rhizopods, almost structureless.
We are thus face to face with a situation which has its closest counterpart in the structureless fleets of the seventeenth century. That naval thought should have so nearly retraced its steps in the course of two centuries is curious enough, but it is still more striking when we consider how widely the underlying causes differ in each case.
We do not know, it is said, by what means the structureless viscid substance which we call protoplasm can build for itself a solid bone; we do not understand how an amoeba makes its test; no one understands how anything is done unless he can do it himself; and even then he probably does not know how he has done it.
The name of Chlamydomonas is applied to certain microscopic green bodies, each of which consists of a protoplasmic central substance invested by a structureless sac. The latter contains cellulose, as in ordinary plants; and the chlorophyll which gives the green colour enables the Chlamydomonas to decompose carbonic acid and fix carbon as they do.
By this important differentiation of the plasson into nucleus and cell-body, the organised cell was evolved from the structureless cytode, the nucleated from the unnucleated plastid. That the first cells to appear on the earth were formed from the Monera by such a differentiation seems to us the only possible view in the present condition of science.
Not only do these almost structureless Protozoa unite into regular or irregular aggregations of various sizes, but among some of the more organized ones, as the Vorticellæ, there are also produced clusters of individuals united to a common stem.
The protozoa include also the flagellata, a great, very poorly defined mass of forms occupying the boundary between the plant and animal kingdoms. They are usually unicellular, and their protoplasm is surrounded by a thin, structureless membrane. This prevents their putting out pseudopodia as organs of motion.
It is a minute spheroid in which the best microscope will reveal nothing but a structureless sac, enclosing a glairy fluid, holding granules in suspension. But strange possibilities lie dormant in that semi-fluid globule.
One might infer already that if the ether were structureless, physical laws operative upon such material substances as atoms could not be applicable to it, and so indeed all the evidence we have shows that gravitation is not one of its properties.
For this reason the natural history of the Monera is of great interest; here alone can we find the means to overcome the chief difficulties of the problem of spontaneous generation. The actual living Monera are specimens of such organless or structureless organisms, as they must have boon formed by spontaneous generation at the commencement of the history of life.
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