'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 medusaB 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. Rouland, Minister of 

 Public Instruction in France. 



TO PROFESSOR AGASSIZ. 



PARIS, August 19, 1857. 

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

 chair of paleontology in the Museum of Na1 

 ural History in Paris becomes vacant. Yoi 

 are French ; you have enriched your native 

 country by your eminent works and laborious 



