1. A Pseudospora individual may adopt three forms--an amœboid, a flagellate, and a radial form. This last, at least, appears to be a direct reaction to external conditions.

2. A single nucleus is present. It is bounded by a membrane, which contains the karyosome surrounded by a clear space; fine rays pass from the karyosome to the membrane.

3. The nucleus divides by mitosis. The chromatin forms chromosomes, which are apparently rod-shaped. The spindle appears to be formed from the achromatic intra-nuclear substance.

4. Pseudospora reproduces by fission. After fourteen to twenty-one days gametes are formed.

5. Gametogenesis. The nucleus of the Pseudospora becomes converted into a sphere, the nuclear substance of which appears to be derived from the rays of the original cell nucleus. The karyosome is extruded from the sphere.

6. The sphere segments to form a large number of gametes.

7. The gametes conjugate in pairs, forming zygotes, which develop into the adult Pseudospora.

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