NATURALIZATION OF FISHES. 199 



weighing a million and a half of pounds, or seven hundred 

 and fifty tons. At the retail price in Boston these would 

 be worth $250,000. Mr. Clark has a pound with an area 

 of an acre and a half, six feet deep, made by enclosing 

 with stakes a portion of Detroit river, in which he keeps 

 white-fish from November until the last of the winter, 

 when they are caught out and marketed. They are first 

 taken with a seine before they have spawned, and most of 

 them spawn here in the pound. The operation is in the 

 following manner : the opposite sexes approach each other, 

 turning partially on the side, and the male appearing to 

 attach himself by his soft flexible mouth to the female near 

 her gills; then both fish dart off through the water 

 together, and as they go the female ejects the eggs and 

 the male the milt, in such a way that they mingle together 

 and fall to the bottom. They move ten or twenty feet at 

 a time, and each time eject several hundred eggs. Mr. 

 Clark placed sieves on the bottom at night, and in the 

 morning found many thousand impregnated eggs on them. 

 Mr. Clark has taken the pains to procure, pack, and send 

 to us two separate lots of these eggs, to assist us in ascer- 

 taining the best mode of packing and transportation Of 

 the first lot, packed in cotton batting, in sand and in river 

 grass, a few survived the journey, out of fifty thousand ; 

 but of the other lot, packed in river mud and partially 

 frozen, not one survived.* Further experiment would, no 



* The only mode of obviating this destruction of ova in trans- 

 portation, is to have them partially incubated before sending them 

 away. 



