These phases are described in your text. Strict anaerobes grow at the bottom of the shake, where the environment is the most anaerobic. Facultative anaerobes grow throughout the medium as they can grow in both aerobic and anaerobic environments. They are placed upside down in the liquid medium. In the illustration, BLUE is the color of the medium that it starts with.
RED indicates that acid has been produced.
The blue squiggly circles represent gas bubbles formed by bacteria that are fermenters. Each of these changes are used to identify different bacteria. Figure 1D illustrates an anaerobic jar. Once that is complete, the valve is turned, again, and hydrogen is pumped into it, rendering the atmosphere in the jar anaerobic. The valve is turned to seal it from all gas sources, then the jar is incubated.