This 1975 photograph shows a large GasPak™ jar with its lid secured. The contents include plates, tubes, wire rack, GasPak™, and an indicator strip. The GasPak™ employs a chemical reaction that generates hydrogen gas. In the presence of a catalyst, the hydrogen gas will react with free oxygen in the air to form water. The GasPak™ jar is used to create an anaerobic environment, which means an atmosphere free of oxygen, in which organisms that thrive under such conditions may be cultivated in the laboratory. Clostridium spp. bacteria, which includes Cl. botulinum, i.e., the cause of botulism, are examples of obligate anaerobic organisms, meaning that they cannot thrive in an environment containing molecular oxygen. For another view of a GasPak™ jar, see PHIL 14909.