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.

[Illustration]

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 Zooelogy 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 we