Eubacteria are prokaryotes, which means they lack nuclei, mitochondria, and chloroplasts, and have a single circular chromosome. Members of this group have rigid cell walls, and are incapable of carrying out meiosis; their reproduction is primarily asexual. Eubacteria are classified into groups based on shape [bacilli (rod-shaped), cocci (sphere-shaped) and spirilla (curved wall)], their ability to form spores, their method of energy acquisition, and even their reaction to a test called the Gram stain. This latter test distinguishes bacteria into gram-negative and gram-positive groups based on their ability to retain crystal violet, with gram-positives being those bacteria that are stained. Since the Eubacteria are so diverse, we have divided them into 8 groups.