organisms are, in many respects, of the highest interest. For the albumen-like, organic matter meets us here as the material substratum of all life-phenomena, apparently not only under the simplest form as yet actually observed, but also under the simplest form which can well be imagined. Simpler and more incomplete organisms than the monera cannot be conceived. ... Indeed, the whole body of the monera, however strange this may sound, represents nothing more than a single, thoroughly homogeneous particle of albumen, in a firmly adhesive condition. The external form is quite irregular, continually changing, globularly contracted when at rest. Our sharpest discrimination can detect no trace of an internal structure, or of a formation from dissimilar parts. As the homogeneous, albuminous mass of the body of the moner does not even exhibit a differentiation into an inner nucleus and an outer plasma, and as, moreover, the whole body consists of a homogeneous plasma or protoplasma, the organic matter here does not even reach the importance of the simplest cell. It remains in the lowest imaginable grade of organic individuality." Prof. Haeckel afterward says: "The monera are indeed protista. They are neither animals nor plants. They are organisms of the most primitive kind; among which the distinction between animals and plants does not exist."
a, Pale, unaltered Chlorophyll Corpuscles of Nitella; b, Others lying side by side with former, but larger, of a darker green, and slightly granular; c, Decolorization advancing a few granules still green; d, Similar corpuscles after the protrusion of motionless rays, and formation of a vacuole; e, Similar corpuscles completely decolorized and converted into sluggish specimens of Actinophrys; f, First stage in transformation of Actinophrys. some of which are converted into Amoebae (g), and others into Monads (h) with two flagella; j, Enchelys-like organisms, probably derived from further development of some Monads and Amœbæ.
The common amœba is described as a microscopic animal at the very bottom of the scale of living things. It is a minute, shapeless, structureless mass of semi-fluid jelly or protoplasm, without organs of any kind, but it has the marvellous power of extemporizing organs as it requires them. Thus, if it wishes to move, it shoots out a part of its body as a temporary foot, and retracts it when no longer wanted.