Likely a sterile medium means an uncontaminated culture (food free of living organisms) that will grow only the new bacteria introduced for analysis. Source(s): http://www.thefreedictionary.com/sterile
Stonepelt was Bluestar's first mentor and a very well-respected senior warrior of ThunderClan. It is revealed in this book that he took her to the Gathering on her second day as an apprentice because she had caught a squirrel very well for a new apprentice, and the squirrel had been as big as she was.
Warriors : Ashencloud's path. Ashenkit, born to Turtleflare and Grayhawk was a kit always bullied by the older kits had always wanted to be a warrior no matter what. As an apprentice she was almost always beaten in training spars and ever felt like she belonged. Ashenpaw wanted to find out where her true destiny lay.