340 



THE AMERICAN NATURALIST [Vol. XLIV 



iveness. The method of putting out glass 3 for the re- 

 ception of fixed forms of animal life I had already be- 

 come acquainted with at St. Andrews while working on 

 .the clam, but the present was the occasion to try every 

 means that could be devised and quickly applied. I ac- 

 cordingly took what objects could be easily procured and 

 constructed and set out traps calculated to capture full- 

 grown larval oysters at the time of their fixation. The 

 idea is the same throughout all forms of the method ; the 

 particular turn in application was my own. Window - 

 glass was cut into strips 2x6 inches so as not to be too 

 big to use on the stage of a compound microscope, the ad- 

 vantage of glass being that one can use either transmitted 

 or reflected light and can turn it over so as to see, through 

 the glass, the attached side of the oyster. These strips 

 were stood on end in deep crocks, about a dozen in each 

 crock, and kept from falling against one another by wire 

 racks, the object of placing them vertical being to mini- 

 mize the aggregation of sediment on their surfaces. The 

 traps were then planted at various places where there 

 were oysters— off Curtain Island where the oysters were 

 large, and off Ram Island Point where there were many 

 sizes of young oysters. The crocks were sunk in gravel 

 just below low-tide level and made secure against the 

 buoyant force of water and the lateral action of waves 

 and currents by building stones around them but leaving 

 the tops open. It was thought that larvae, either swim- 

 ming about or swept about by the waves, might drop into 

 the crocks where the water would be comparatively still 

 and find it easy to cling to the glass during the first stages 

 of fixation. 



Ram Island Point appeared to be the most favorable 

 place and that was about six miles from the station, but 

 daily visits were made, the strips of glass were one by 



3 Ryder, Comm. Fish. Maryland, 1881, p. 57; Bull. U. S. Fish Comm., 



1883. Winslow, Bull. XL S. Fish Comm.", 1884^ p. 354. Jackson, Science, 

 1888, p. 230 (Vol. XI, No. 275) ; Mem. Bost. Soc. Nat. Hist., 1890, p. 285. 



