The Animal Parasites of Man by Fantham, Braun, Stephens, and Theobald

1. The infection begins with _elementary bodies_ or _elementary

corpuscles_ which live at first extracellularly. An elementary body is a minute speck of chromatin, apparently devoid of cytoplasm, which can pass through a bacterial filter. It can enter a host cell, but the entry is not a process of phagocytosis.