The Lesson of the Diatoms presented objectively has much to offer, and could perhaps add more to the general biology course than is frequently realized. Its value consists in portrayal not only of their features, but of their place in Nature. It embraces relationships of most compelling interest and most profound significance, not to use superlatives inadvisedly. Show of their varied beauty, description of their unique characteristics, and statement of their commercial importance, which often comprise their classroom introduction, should not be allowed to obscure a still greater entity. Full worth of their acquaintance lies in abstract values beyond the bare confines of the subject. These concern vast ecological relationships, involving basic principles of biology. To miss such broader values is to miss an opportunity for larger benefits of which this lesson is capable. The story of the diatoms can be as dynamic as are the surges of the lakes and oceans in which they live. To be effective it should be told in its entirety. Treatment of the diatom as a botanical type is not enough. It is inseparably associated with ecology and oceanography, geology and industry, fisheries and conservation. In this integral complex lie its excitement and its cultural value. 'Viewed thus it opens the whole vista of aquatic biology. A subject whose theme is so definitely ecological calls for presentation in well-coordinated perspective. The essence of ecology is its comprehensiveness. A surprisingly large number of persons do not know that diatoms exist. People frequently ask: are diatoms? Are they living to day? What do they do? This unawareness is probably due to their microscopic character, and the indirectness of their effect upon us. Even among biology students there exists considerable unrealization of the scope of their significance. Yet diatoms are tremendously abundant, widely distributed, and of greatest importance in the balanced economy of the aquatic world. There is small point in learning isolated facts about diatoms, however curious and interesting, if one fails to get a lasting, overall picture of the greater biological system of which they are such an important functional part. Details alone, about their types, structure, reproduction, habits of growth, etc., are not destined to make a student a better citizen, more capable of enjoying life, or potentially well informed, (traditional goals of education); he will neither be impressed with nor remember these, but a unified and well told story of the life of the diatoms and their interrelationships and role in Nature can, with benefit, do all of these. More of the philosophy as well as the facts of the subject could perhaps strengthen both its teaching and its comprehension. The facts of diatom character are simple, and hardly need repetition to biology teachers; objectives and manner of presentation might be enhanced. Toward the aim of a realistic ecological picture I propose to skip routine facts and pass on to less recognized relationships, and to append some possibly helpful teaching aids.