Solid gels made from agar have long been a standard tool in the study of microbes. Scientists make them up to include various nutrients, and then grow colonies of microbes on their surface. Agar gels have several important advantages over the original growth medium, which was gelatin. Very few bacteria can digest the unusual agar carbohydrates, so agar gels remain intact and the bacterial colonies separate, while many bacteria digest proteins and can quickly liquefy a gelatin gel into a useless soup. And agar gels remain solid at the ideal temperatures for bacterial growth, often around 100ºF/38ºC, a temperature at which gelatin begins to melt.