32 COMMISSION OF CONSERVATION 



when they would all die off. As long, I suppose, as the oyster has 

 been known to man, it has been known that, under normal con- 

 ditions, it is attached to some solid body in the sea-water. By trac- 

 ing back through smaller, younger oysters, fishermen and culturists were 

 able to arrive at comparatively small specimens, perhaps but little smaller 

 than a man's thumb-nail, which, along with all other small sizes, had been 

 called "spat". It was found also that, by placing solid bodies such as 

 stones, shells, bones, tiles, lumber, ropes or other objects in the water near 

 oyster beds, a "set" of spat could sometimes be secured. The spat 

 recognizable by fishermen and others unacquainted and unprovided with 

 microscopic appliances were somewhat large objects, but a few expert 

 zoologists had succeeded in procuring several very young spat. These 

 were at least five times the length and one hundred and twenty-five times 

 the volume of the larvse reared by artificial fertilization and culture. The 

 intermediate stages were unknown. The character of these stages, the 

 place of occurrence, the time of the year, the length of the period, and 

 the manner of existence were alike unknown. It may have been con- 

 jectured that they lie on the bottom or become set to rocks, shells or 

 weeds, or that they float about somewhere in the water. At least these 

 are some of the possibilities that occurred to me and called to mind my 

 former observations on mussel larvse, as already outlined in the intro- 

 duction. I accordingly began the first systematic use of the plankton 

 net in the search for oyster larvae, and it resulted in discovering all the 

 stages between the oldest veligers that had been known and obtained by 

 culture and the youngest natural spat that had been procured on glass, 

 shells, etc., in the sea. 



In a brief preliminary account of what I regarded at the time as the 

 most important results of my first summer's work occur the following 

 statements about the larval oyster in its oldest plankton stages: 



"We have been accustomed to think of it as vastly different from 

 other bivalve-larvae, corresponding to the early assumption of a sessile 

 mode of life. This misconception is due to lack of observation of plankton 

 stages, embryologists having jumped from early veliger or phylembryo 

 to late prodissoconch or even early nepionic periods." — (Amer. Nat., Jan. 

 1905, p. 41). 



The plankton was collected in nets made of fine-meshed, silk bolting- 

 cloth, cut and sewed so as to be conical in form, with smooth overturned 

 seams, without unnecessarily exposed needle-holes, and with no folds. 

 To take the wear, a double band of strong linen was used to attach the 

 broad end of the net to a thin but firm iron hoop, one foot in diameter. 

 A similar band strengthened the small end of the net, which was of just 

 sufficient size to slip over the neck of the broad-mouthed bottle and be 

 fastened by tying a string around it. To the hoop were attached three 



