CHAPTER 18.

1855-1860: AGE 48-53.

"Contributions to Natural History of the United States."
--Remarkable Subscription.--Review of the Work.--Its Reception in
Europe and America.--Letters from Humboldt and Owen concerning it.
--Birthday.--Longfellow's Verses.--Laboratory at Nahant.
--Invitation to the Museum of Natural History in Paris.--Founding
of Museum of Comparative Zoology in Cambridge.--Summer Vacation in
Europe.

CHAPTER 19.

1860-1863: AGE 53-56.

Return to Cambridge.--Removal of Collection to New Museum Building.
--Distribution of Work.--Relations with his Students.--Breaking out
of the War between North and South.--Interest of Agassiz in the
Preservation of the Union.--Commencement of Museum Publications.
--Reception of Third and Fourth Volumes of "Contributions."--Copley
Medal.--General Correspondence.--Lecturing Tour in the West.
--Circular Letter concerning Anthropological Collections.--Letter
to Mr. Ticknor concerning Geographical Distribution of Fishes in
Spain.

CHAPTER 20.

1863-1864: AGE 56-57.