Petri Dish Lid

This object is a petri dish lid with a circular paper grid featuring the numbers 1–50 taped to it. The paper grid was photocopied out of a laboratory manual, most likely one published by the Cold Spring Harbor Laboratory or Maniatis Laboratory.

The lid was used in the laboratory at Genentech, a biotechnology company, as a way to distinguish between bacterial colonies. It was placed under a clean petri dish, and bacterial colonies were transferred onto the dish, one colony per grid square. Colonies could then be tracked using their grid number. A small sample from each colony could be removed and tested to give the characteristics of the entire colony. This system was essential at Genentech where often scientists needed to keep track of 100s to 1000s of colonies per research project.

Source:

Interview with Dan Yansura, Genentech scientist, 12/20/2012

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