410 A CENTURY OF SCIENCE 



the southeastern coasts and Gulf of Mexico under the 

 leadership of Pourtales and Agassiz. 



The Challenger explorations (1872-1876) added greatly 

 to the knowledge of marine life off the American coast 

 as well as in other parts of the world. 



The explorations of the United States Fish Commis- 

 sion succeeded those of the Coast Survey in the collection 

 of marine life off our coasts and in our fresh waters. 

 These have continued since 1872 and have yielded most 

 important results from both the scientific and economic 

 standpoints. 



Under the charge of Alexander Agassiz the Coast Sur- 

 vey Steamer " Blake," in 1877 to 1880, was engaged in 

 dredging operations in three cruises to various parts of 

 the Atlantic. The U. S. Fish Commission Steamer 

 " Albatross," also in charge of Agassiz, made three expe- 

 ditions in the tropical and other parts of the Pacific in the 

 years from 1891 to 1905. The study of these collections 

 has added greatly to our knowledge of systematic zoology 

 and geographical distribution. The reports on some of 

 the groups are still in course of preparation. 



Period of Evolution, 1870-1890. 



The time from 1870 to 1890 may be appropriately called 

 the period of evolution, for although it commences eleven 

 years after the publication of the Origin of Species, the 

 importance of the natural selection theory was but slowly 

 receiving general recognition. The hesitation in accept- 

 ing this theory was due in no small degree to the opposi- 

 tion of Louis Agassiz. After the acceptance of evolution, 

 although morphological and embryological studies con- 

 tinued as before, they were prosecuted with reference to 

 their bearing on evolutionary problems. 



Following closely the methods which had produced so 

 much progress during the life of Agassiz, the field of 

 zoology was now occupied by a new generation, among 

 whom the pupils of Agassiz were the most prominent. 



The teaching of biology at this time was also strongly 

 influenced by Huxley, whose methods of conducting lab- 

 oratory classes for elementary students were adopted in 

 most of our large schools and colleges. This placed 



