union

The fusion of two c's to form a single new c. This is the e ential proce in the sexual reproduction of plant and animal c's. The two uniting c's may be of about the same size and appearance (in which case the proce is usually called c. conjugation), or may be different in size and other characteristics. In the latter case, the smaller c. is usually the more actively motile, and seems to act by stimulating the larger and more stable c. to development, and is hence regarded as homologous with the similarly acting spermatozoid of the higher animals, and is called the male reproductive c. central c's. Of the stomach cells.