66 LOUIS AGASSIZ 



plete. In the laboratory at NeuchAtel 

 were carried on some of the earliest 

 experiments in artificial fish-breeding 

 a subject which has now grown to vast 

 commercial importance. The fossil echi- 

 noderms of the Jura had not been ade- 

 quately treated ; and, therefore, Agassiz 

 could not resist writing an extensive 

 monograph on the subject, which soon 

 interested him in living echinoderms. 

 It occurred to him that the inner shape 

 of shells was very little known, and that 

 castings to give at least the outline of the 

 inhabitant would be of special value for 

 the extinct mollusks who have left us 

 shells and nothing else. No sooner was 

 it thought than done. Experiments on 

 metallic alloys which can -fill without 

 shattering, the preparation of shells to 

 act as moulds, and then the careful cast- 

 ing of models all were carried on under 

 Agassiz's eye and at his expense ; but in 

 this particular case there were actually 

 some pecuniary returns, as various mu- 



