Lesley.] 5JJ ^y^.^^. j^^ 



his attention. Ilis sysleniiitiziition of Alpine ranges is wholly topograph- 

 ical ; not at all mineralogical, much less plutonic. In my many conver- 

 sations with him I heard no theory escape his lips which went deeper 

 than the erosion of the surface, nor was Elie de Beaumont ever alluded 

 to. His orography was essentially systematic and descriptive. 



He accompanied Elie de Beaumont to the meeting of the Helvetic So- 

 ciety, at Xeufchatel, in 1837, and tliere became acquainted with Ag-assiz ; 

 and this l)ecame the turning point of his intellectual life. But the first re- 

 sult of the influence which Agassiz exerted over liim was hostile to any 

 train of thought suggested to him by Elie de Beaumont. It drew him first 

 into the study of the fossil forms in the rocks of the Jura Mountains, and 

 then into the study of the glaciers of the Alps. It was not until Desor 

 joined the corps of Pennsylvania geologists, in 1852, that his eyes were 

 really opened to the wonderful phenomena which had long before inspired 

 the genius of Elie de Beaumont to reconstruct the fundamental axioms 

 of structural geology. In fact, the bent of Desor's mind was for investi- 

 galing the forms and habits and metamorpho.ses of the animal world ; and 

 the large way in which he afterw^ards pursued these studies was due not 

 to the instructions of Elie de Beaumont in Pari.s, but to the influence of 

 the superior genius of Louis Agassiz in Neufchatel, and through Agassiz 

 of that coryphgeus of modern science, Agassiz's great master, Cuvier. 



After his return from America to Switzerland Desor studied the struc- 

 ture of the Jura Mountains with a clearer vision ; but, while liis definition 

 of structural forms was singularlj^ precise and complete, his theoretical 

 conclusions were always based on more violent hypotheses than those in 

 vogue in the school of Ly ell. He remained to his last days a moderate 

 cataclysmist both as to plication and as to erosion. 



After leaving Paris to take up his permanent residence in Switzerland 

 Desor lived for a short time in the house of Professor Vogt, the father of 

 Karl Vogt, in Berne. At one of the annual reunions of the Helvetic So- 

 ciety of Natural Sciences Vogt introduced Desor to Agassiz, who induced 

 him to settle in NeufchStel. Agassiz, born in 1807, was only 4 years older 

 than Desor, and they soon established a close brotherhood in society and 

 science, which lasted nearly twenty years. Agassiz had studied"medicine 

 at Zurich, Heidelberg and Munich ; but by a curious accident, which he 

 was fond of narrating, his residence in the same house with an old man 

 Avhose rooms were filled with preparations of fish, Agassiz became enam- 

 ored of that special branch of Natural History ; had studied the fisli 

 brought from Brazil by Martins & Spix, and published his Latin descrip- 

 tion of them in 1829-31 ; and was appointed Professor of Natural History 

 at Neufchatel in 1832, where he was now in the full tide of his researches 

 into the nature and distribution of fossil fish. It was during a visit to 

 Paris that Agassiz made friends with Cuvier and Humboldt ; and at Paris 

 liis great work on the Classification of Fish went through the i>ress during 

 the ten years from 1832 to 1842. 



The summer vacations of Agassiz were si ent on the glacier of the Aar. 



