ACADEMY OF NATURAL SCIENCES. 319 



Commercial Interests of the Pacific States, from J. H. Carmany. 

 Essai Politique sur la Nouvelle Espagne, by A. de Humboldt, 2 

 Vols., 4to., and atlas folio, Paris, 1811, presented by A. Sutro. 



Professor Whitney read the following communication : 



On the Fresh Water Infusorial Deposits of the Pacific Coast, 

 and their Connection with the Volcanic Rocks. 



BY J. D. WHITNEY. 



The microscopic discoveries of the last few years have immensely extended 

 the range and importance of the minute, and, to the naked eye, invisible organ- 

 isms, which, under the general designation of " Infusoria/' are recognized as a 

 part of the kingdom of nature. It is especially to Ehrenberg that we are in- 

 debted for a demonstration of the geological importance of the Diatoms, those 

 microscopic organisms which so long puzzled naturalists to decide whether they 

 were animal or vegetable in their nature, but which are now, by the majority 

 of zoologists, referred to plants. In Ehrenberg's great work, the " Mikrogeol- 

 ogie," or geology in little, this eminent naturalist has given the results of the 

 examination, by himself, of specimens of infusorial rocks, soils, ashes, dust, and 

 other accumulations or masses of matter from every quarter of the globe : 

 these investigations show most conclusively that deposits of vast extent — of 

 such magnitude, indeed, as to form no inconsiderable portion of the earth's 

 crust — are the result of organic agencies, and that what seems to the eye an 

 unorganized mass, may in reality be made up of the delicately wrought and 

 almost infinitely minute remains of plant or animal life. 



That animals, or plants, so minute that a hundred millions of distinct indi- 

 viduals will scarcely weigh a single grain, should form accumulations hundreds 

 of feet in thickness and extending over thousands of square miles, seems a 

 hardly credible statement ; but a fact still more difficult to believe and com- 

 prehend is one which is thoroughly established by abundant evidence, namely : 

 that immense deposits of volcanic materials, or, at least, of materials closely 

 connected in their origin and nature with volcanic action, and spread over vast 

 tracts of country in different parts of the world, are also, to a large extent, 

 made up of these microscopic organisms, the existence of which seems de- 

 pendent on the" presence of water, and so utterly at variance with a condition 

 of volcanic activity. 



Throughout this volcanic region of California, Oregon, Nevada, and proba- 

 bly as far north as the igneous masses extend, which are well known to cover a 

 vast area on the western side of our continent, there are found deposits, which 

 are usually called "fire-clay," "kaolin," " pipe-clay," or simply " clay;"* these 

 masses are, however, not at all of the nature of kaolin, nor are they proper 

 clay, although they may, in places, pass into clay or shale. 



♦They are also frequently called "magnesia," and have been repeatedly stated by " assayers " 

 in San Francisco to be made up of that earth. 



