You will want to know how these leaves grew, and it is in this way. First a little free swimming animal, a mere living sac provided with lashes, settles down and grows into one little horny alcove, with its live creature inside, which in time sends off from it three to five buds, forming alcoves all round the top and sides of the first one, growing on to it. These again bud out, and you can thus easily understand that, in this way, in time a good-sized leaf is formed. Meanwhile the creatures also send forth new swimming cells, which settle down near to begin new leaves, and thus a tuft is formed; and long after the beings in earlier parts of the leaf have died and left their alcoves empty, those round the margin are still alive and spreading....
If you can trace the spore-cells and urns in the seaweeds, observe the polyps in the Sertularia, and count the number of mouths on a branch of my animal fringe (Sertularia tenella); if you make acquaintance with the Thuricolla in its vase, and are fortunate enough to see one divide in two; if you learn to know some of the beautiful forms of diatoms, and can picture to yourself the life of the tiny inhabitants of the Flustra; then you will have used your microscope with some effect, and be prepared for an expedition to my pool, where we will go together some day to seek new treasures.
NOTES
Agassiz, J.L.R., naturalist, born in Switzerland, 1807; died, Cambridge, Mass., 1873. In 1846 he came to America, after having gained a high reputation in Europe, to deliver a course of lectures in Boston "On the Plan of the Creation," and met with such success that he spent the rest of his days there, declining an invitation to return to his native country and to Paris. In 1848 he was elected to the chair of Natural History at Harvard. In 1850-51 he went on an expedition to the Florida Reefs. In 1858 he founded and organized the Museum of Comparative Zoölogy at Cambridge—and, later on, went on his important voyage to Brazil. In 1872 he founded and organized the summer school of Natural History at Buzzard's Bay. He wrote "The Fishes of Brazil," "A Study of Glaciers," "Natural History of the Fresh Water Fishes of Central Europe," "Contributions to the Natural History of the United States" (unfinished), and with his wife, "A Journey in Brazil."
Ball, Prof. Sir R.S., English astronomer, born in Dublin, 1840. Was appointed Lord Ross's astronomer in 1865. Professor of mathematics and mechanics at the Royal Irish College of Science in 1873, and is now astronomer royal for Ireland. He is the author of "The Story of the Heavens," "Starland," etc., and is well known as a successful lecturer on astronomical subjects in this country.
Darwin, Charles R., English naturalist, born, 1809; died, 1882. He first formulated what is known as the principle of Natural Selection. In 1831 he went in the famous scientific voyage of the Beagle as naturalist, and afterwards published an account of it. He was one of the most thorough, careful, and painstaking scientific men of this or any age. He is the author of many famous books. "The Origin of Species," "The Descent of Man," "Insectivorous Plants," "The Power of Movement in Plants," "The Structure and Distribution of Coral Reefs," "Geological Observations on Volcanic Islands." "The Formation of Vegetable Mould" was his last published work.
Flammarion, C., famous French astronomer, born, 1842. He has written many popular works on astronomy, most of which have been translated into English. "The Stars," "The World Before the Creation," "Uranus," "Comets," "Popular Astronomy," are among his best known.
Holden, Prof. E.S., American astronomer, born at St. Louis, 1846. Lieutenant engineers, U.S.A., 1870-73; professor mathematics, U.S.N., 1873-81; director Washburn Observatory, 1881-85; president University of California, 1883-88; director Lick Observatory, 1888-98. Is a member of several learned societies of Europe. Is the author of a "Life of William Herschel," "A Hand-book of the Lick Observatory," "Earth and Sky," "Primer of Heraldry," "Elementary Astronomy," "Family of the Sun," "Essays in Astronomy," "Stories of the Great Astronomers," etc.