“Ecology,” as it is coming to be universally considered, is the science of cause. It is constantly asking “Why?” and not until we can answer “because,” have we solved a problem in Ecology. It is the capping stone of the other branches of biological investigation. Morphology describesan organ or character; physiology shows us how it works and what it does; ecology, building on these, tells how and why the character or organarose. It, then, must be considered as more than the o1d Natural History. Although the value of the latter cannot be overestimated, more must sooner or later be done.