H., Philadelphia, sends us an extract from a California paper, showing that a Eucalyptus globulus stood in Oregon, and without injury, when the thermometer fell 17° below freezing point, and asks "why it would not do as much in Philadelphia." "We are nearly tired of this Eucalyptus matter. If people want to plant Eucalyptus trees here in the East, we know of no law against it. As our friend, Mr. Price, told us last year, they do not try the experiments at anybody's expense but their own. But if we must answer our correspondent's question we should say, as the child says,"It won't live in Philadelphia at the same temperature as in Oregon, because it won't." Hardiness, as most of our readers know, is not decided by the thermometer.