ZOOLOGY. 275 



The tide, which there runs from N. TV. to S. TV., and from S. TV. to 

 N. TV., at the rate of about three miles an hour, keeps the water con- 

 stantly renewed, and carries off all unhealthy deposits, and contracts, 

 by breaking against the rocks on the shore, the necessary vivifying 

 properties. The immersion of the breeding oysters was commenced in 

 March, and concluded about the end of April, during which time about 

 3.000,000 of oysters, taken some from the sea, were distributed in ten 

 longitudinal beds in different parts of the bay, forming together a su- 

 perficies of 1000 hectares. The position for these banks had been, 

 traced out beforehand on a chart, and floating flags were placed to di- 

 rect the movement of the vessels engaged in the operation. In order 

 that the immersion of the oysters should be made with perfect regular- 

 ity, and th#t the female oysters should not be injured by lying too 

 thickly one over the other, two steamers, towing boats laden with oys- 

 ters, proceeded from one end of the bank marked out to the other, 

 letting down the oysters as they wgnt, and then, when reaching the 

 other end, turning round and retracing their way, thus distributing the 

 fish with as much regularity as a plough could turn up a furrow in a 

 field. After having laid down the oysters in conditions most favorable 

 for their multiplication, it was necessary to organize around and over 

 them prompt means for collecting the spawn, and constraining it to fix 

 itself on the spot. One of the plans adopted to accomplish this object 

 was to cover the bottom of the new bed with old oyster shells, so that 

 not a single embryo could fall without finding a solid body to fix itself 

 to. The second plan, as already stated in a former report, was to 

 place long lines of boughs of trees, arranged like fascines, from one 

 extremity of each bed to the other. These fascines were ballasted by 

 a weight placed at the bottom, and the tops of them when fixed in their 

 position, stood about eighteen or twenty inches above the bed of oys- 

 ters, and thus prevented any of the spawn from being carried away by 

 the current. These fascines were placed by men with diving dresses. 

 As the cords with which the fascines were at first fastened would soon 

 wear out, the report states that they may hereafter be replaced by 

 small chains of galvanized iron, manufactured for the purpose in the 

 arsenals of the State. The most exact indications have been made on 

 the chart of the bay, so that the fascines may be taken up as regularly, 

 in order that the oysters attached to them may be collected, as a far- 

 mer could pick the fruit from his trees. The report then goes on to 

 say that, although six months have scarcely elapsed since the operations 

 were performed, the result has exceeded the most sanguine expecta- 

 tions. The fascines have on their branches such clumps of oysters 

 that they resemble trees in an orchard, the boughs of which are 

 in the spring hidden by the exuberance of the blossoms. 



INSECT VISION. 



The following article is communicated to the Intellectual Observer, 

 by Hon. Richard Hill, of Jamaica : In setting up a collection of 

 crickets, locusts, and grasshoppers, we see that there is a prevailing 

 color, as marked and as intense in the eyes as in the body ; thus, lo- 

 custs are red ; grasshoppers green ; and crickets black ; and their eyes 

 are of similar decided hues. Are we to infer that objects to them 

 have the same tint as these hues of the choroid ? Are they colored as 



