In what conditions are the bottles stored? Why?
The storage of the bottles that hold human embryos is organized into who they are meant to be when they are decanted (or born). Each class of society goes through different heating and cooling systems as they go down the conveyor belt before storage; they also go through other conditioning procedures depending on where they will live out their lives. But by the time they come off the assembly line and are stored on different racks. For example, Rack 10 holds the "next generation's chemical workers [who] were being trained in the toleration of lead, caustic soda, tar, [and] chlorine" (18). Future rocket engineers end up on Rack 3 while Alpha Plus Intellectuals await decantation on Rack 5 on the "First Gallery level" (19). By organizing the bottles this way, they keep the social classes separate from each other so each can be stored under the conditions that will make them happiest for their predestined circumstances.
The bottles are stored in the same way the society is organized; this means members of the society are categorized before birth and their lives determined at that point. The purpose for this high level organization is to genetically condition the embryos to fit into the particular lifestyles and life activities that they will be involved in. Each individual has a specific role to play within the society and they are expected to play these roles happily since the society is based on happiness and entertainment. Conditioning before birth is thus essential to ensure each individual fits happily in their environment after birth. This helps the society to stay organized just like the incubating racks of the embryos. For instance embryos of individuals who would become engineers are kept in motion in preparation for their lifetime work in weightless environments.