HISTORICAL DEVELOPMENT OF ZOOLOGY 447 



reaching the truth on account of their carelessness in opera- 

 tion, but it was finally shown that no animalcules appeared 

 in water which had been boiled thoroughly and sealed so that 

 no germs could enter. The final conclusive experiments 

 were those of Pasteur (1822-1895) about 1860, and those 

 of Tyndall (1820- 

 1893) a few years 

 later. 



An important step 

 in paleontology was 

 made when Boucher 

 de Perthes, in 1836, 

 found flint axes in 

 northern France so 

 far beneath the sur- 

 face of the ground 

 that it pointed to- 

 ward a greater an- 

 tiquity for man than 

 had hitherto been 

 believed. Though 

 combated by many, 

 the truth finally 



prevailed, and 



, FIG. 232. Louis Agassiz 



man s presence in 



Europe was proven at least as far back as glacial times. 

 Louis Agassiz (1807-1873, Fig. 232) is famous both as an 

 investigator along many different lines and as an inspiring 

 teacher. He was born in Switzerland, near Lake Neuchatel, 

 and after study in Europe came to America at the height 

 of his reputation in 1846, where he remained during the rest 

 of his life. He became connected with Harvard University 

 in 1847, and the Museum of Comparative Zoology at Cam- 

 bridge, Massachusetts, is a monument to his enthusiasm and 



