170 THE AMERICAN NATURALIST. (VoL. XXXII. 
he came to America in 1846 to give a course of Lowell Insti- 
tute Lectures in Boston, which he had been invited to do upon 
the recommendation of Sir Charles Lyell. With imperfect 
knowledge of English he succeeded in holding immense audi- 
ences on the general subject of “The Plan of the Creation, 
especially in the Animal Kingdom.” The course was a marked 
success, notwithstanding his unfamiliarity with the English 
language. But it was followed by one more to his liking, 
given in the French language, upon “Les Glaciers et l’ Epoque 
Glaciaire.”’ From this time on the incidental observations of 
the great naturalist upon glacial phenomena became a most 
important part both of his own work and of the po litera- 
ture of the subject. 
In 1848 Agassiz made his celebrated excursion to Lake 
Superior in company with a small party of Harvard College 
students and Boston gentlemen. In a remarkable volume, 
now difficult to obtain, which resulted from this expedition, 
there is to be found a great wealth of glacial observations 
made at every stage of the journey. It was indeed a grand 
verification of his original theory. In 1864 Agassiz made an 
extended excursion in Maine, and brought back an immense 
amount of material in support of his glacial theory. The Az 
lantic Monthly, in an article entitled “ Glacial Phenomena of 
Maine,” contains his report upon the moraines and eskers and 
kames which there so reminded him of similar phenomena in 
his native country. The abundant later literature upon the 
subject is little more than a commentary upon these original 
observations of the great promulgator of the glacial theory. 
In 1865 and 1866 Agassiz made extended explorations in 
Brazil mainly in the interests of biological science. In a side 
trip, however, which he made amid great difficulties in the 
rainy season in the Province of Ceara, 4° south of the equator, 
he thought he discovered numerous medial, lateral, and frontal 
moraines at an elevation of only eight hundred feet above the 
sea. But it is supposed by later observers that he was misled 
by the resemblance to glacial phenomena which often arises in 
connection with the slow disintegration of granitic masses in 
which the residuary boulders sometimes have a close resem- 
