CREATION BY EVOLUTION
been formed (Fig. 3, B to F.). These five sets are like different branches of a tree, all coming from one trunk. They are separated by many generations from the original parent A. During the passage of these generations the different branches have become permanently diverse. Each differs from the other hereditarily. Even when all are living
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Fig. 2.—Method of reproduction of Difflugia (after Verworn).
The parent A consists of a mass of protoplasm, covered by a rounded shell made of sand grains cemented together. This shell has an enlarged opening (below, in the figures). During its life the parent creeps about at the bottom of pools. It takes up many sand grains, which it stores within its body. At reproduction the protoplasm of the parent swells and projects from the mouth of the shell A. This projecting part enlarges and takes a form similar to that of its parent (at B and C). The nucleus of the parent divides and one-half of it passes into the projecting portion. The sand grains within the parent body also pass out into the projecting mass, come to its surface, and spread over it (C and D). They are embedded in a fluid secretion which now turns hard, forming a shell like that of the parent. The two shells are in contact at their mouths. Now the mass of protoplasm divides into two individuals, which separate, one retaining the old shell (above in the figures); the other having the new shell. Later, each individual repeats this process, producing another generation.
under the same conditions the stocks remain diverse for generation after generation. From the original single stock several hereditarily diverse stocks have been produced. Each set or race included a large number of individuals, all show-
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