AGASSIZ ON FISH BREEDING. 127 



That parasites do destroy the canker-worm and the caterpillar 

 is well known ; the only question is, how man can control these 

 parasites and let them loose upon these destructive insects at 

 pleasure. Providence has fixed a limitation to artificial life, 

 and the more artificial a fruit is, the sooner it reaches its limi- 

 tation by some extraordinary law ; that law which has driven 

 the St. Michael's pear out of New England, which has brought 

 some varieties of the potato to an end, which has crushed down 

 all the buttonwood trees, and which seems to apply to all forms 

 of vegetable life on which man has laid his hands. These are 

 the difficulties against which we have to contend. How ? 

 Simply, as Col. Wilder and Mr. Moore have told you, by the 

 application of the best laws of horticulture in the selection of 

 lands, in the selection of trees, and the application of fertilizers. 

 It seems to me that is perfectly apparent. 

 Adjourned to evening, at 7| o'clock. 



Evening Session. 



The Board met at the hour assigned, and was called to order 

 by Col. Stone, who said : — 



Ladies and Gentlemen, — Owing to an engagement of our 

 honored friend, the Hon. Marshall P. Wilder, to-day, I occu- 

 pied the position that I now hold. He has kindly consented to 

 assume the responsibilities of this position this evening, and 

 I have the pleasure of introducing the Hon. Marshall P. 

 Wilder. 



Col. Wilder. Ladies and Gentlemen, — It affords the Board 

 of Agriculture great gratification to witness this large and 

 highly respectable assembly. But it is not the presence of the 

 Board of Agriculture that has called you together. It is the an- 

 nouncement of a name which not only commands universal 

 respect, but universal honor and gratitude. I beg to introduce 

 as the lecturer of this evening. Prof. Louis Agassiz, a member 

 of the Board. 



FISH BREEDING. 



BY PROF. LOUIS AGASSIZ. 



Ladies and Gentlemen, — The subject selected for this even- 

 ings address is that of Fish Breeding. It is a subject which has 

 of late years attracted considerable attention everywhere, on 



