animals and plants and their development from the germ to the fully adult individual, and special modifications of form and color by which animals are protected from their enemies; the adaptations for peculiar environments and modes of life; the characteristics of youth, maturity, and old age; the variation in form, size, and color among individuals of the same species; the domiciles and other works constructed by birds, mammals, insects, and the like. To these series should be added another of great importance, the Economic Series, representing the animals and plants as related to the activities and needs of man. Any one of these principal series in its full development would more than fill the entire space now available.
3. There should be developed a museum of practical geology in the broadest sense, which will be of service to every producer and consumer of American mineral products, and to all students of geology who are engaged in either economic or purely scientific investigations.
In addition to the series of rocks and fossils illustrating the stratigraphy and succession of the sedimentary rocks and the systematic collection of minerals and ores, an exhibit showing how geologic work benefits the daily life of the people should be developed. An illustration of this would be a representation of the artesian-water supply of the semi-arid region, showing the stratification and structure of the sedimentary rocks, and how hydrographic and geologic investigations clearly indicate the regions in which artesian-water development may be carried on successfully. Mining and areal geology could also be illustrated in such manner as to place before the student and intelligent observer the import and value of such work.
In most museums the principal effort has been to make a collection of useful mineral products. This is desirable, but, from the broad view of illustrating the practical in addition to the scientific side of geology, it should be secondary. The best basis for classification on the practical side of the museum exhibit appears to be the finished mineral product. For instance, if pig iron be taken as a key material in classification, the iron ores from which it has been obtained should be arranged so as to show the various kinds whose combination has resulted in the pig iron. In connection with this should be grouped the geologic phenomena, which should include any geologic conditions connected with the original deposition and the occurrence of iron ores. This might include the conditions which have led to the oxidation of pyrite and other sulphur compounds of iron, and to the development of hydrous oxides of iron; also an illustration of what has been demonstrated
