We have observed that the entire blue phase temperature range for cholesteric mixtures with half-pitch less than 2200Å is comparable to the range of temperatures over which the cholesteric and isotropic liquid coexists when the pitch is greater than 2200Å. The cholesteric-isotropic-blue phase triple point is described. The bätonnets which the larger pitch cholesteric phase nucleates become unstable with respect to the smaller pitch blue phase isotropic mixture. These observations lend support to our previously proposed model that blue phases are cholesteric-isotropic emulsions which are only stable when the pitch is less than 2500Å.