550 LOUIS AGASSIZ. 



friends, the Holbrooks, at this time, " You can 

 hardly imagine what a delightful place Nahant 

 is for me now. I can trace the growth of my 

 little marine animals all the year round with- 

 out interruption, by going occasionally over 

 there during the winter. I have at this mo- 

 ment young medusae budding from their polyp 

 nurses, which I expect to see freeing them- 

 selves in a few weeks." In later years, when 

 his investigations on the medusae were con- 

 cluded, so far as any teaching from the open 

 book of Nature can be said to be concluded, 

 he pursued here, during a number of years, 

 investigations upon the sharks and skates. 

 For this work, which should have made one 

 of the series of " Contributions," he left much 

 material, unhappily not ready for publication. 

 In August, 1857, Agassiz received the fol- 

 lowing letter from M. E-ouland, Minister of 

 Public Instruction in France. 



TO PROFESSOR AGASSIZ. 



PARIS, August 19, 1857. 



SIR, By the decease of M. d'Orbigny the 

 chair of paleontology in the Museum of Nat- 

 ural History in Paris becomes vacant. You 

 are French ; you have enriched your native 

 country by your eminent works and laborious 



