The formation of intracellular glass may help protect embryos from damage due to desiccation. Soluble sugars similar to those found in desiccation tolerant embryos were studied with differential scanning calorimetry. Those sugars from desiccation tolerant embryos can form glasses at ambient temperatures, whereas those from embryos that do not tolerate desiccation only form glasses at subzero temperatures. It is concluded that tolerant embryo cells probably contain sugar glasses at storage temperatures and water contents, but intolerant embryo cells probably do not.