OYSTER PROPAGATION IN P.E.I. 77 
SESSIONAL PAPER No. 38a 
strong winds blow crosswise and they are at the surface, which is not usually true in 
rough weather. Everything depends on the adjustment they make in reference to the 
tides. We have found most fry on the flood tide. This would prove that the tendency 
is to work away from the inlet, and up towards headwaters. 
On August 27, saraples of tarred shells, placed on the 21st on Curtain island 
and Ram Island shoals were taken. Spat were found only on the Curtain island 
shells, on about six out of two dozen shells, and only from one to three spat per shell. 
The spat shell added, ranged in width from 160 mu to 600 mu during the six days’ 
sojourn, thus corroborating our previous calculations. It is of course possible that 
the largest did not “set” at the earliest hour after planting, and so the growth might 
be greater than 100 mu per day. This would not be surprising, since the conditions 
for growth are very good on these current-washed shoals. If the rings of. growth 
seen correspond to diurnal additions, then one spat grew at the rate of 180 mu per 
day. But it has yet to be proved, that the growth of the dissoconch or any other shell 
growth, is adjusted to diurnal rather than tidal variations, or something else. 
On September 3, Robert McKenzie took samples of shells from the McNutt beds, 
which were forwarded to me. Three of the seven shells sent carried spat; two 
“rights” held twenty and fifteen spat, respectively, and one “left” held six spat. 
This distribution suggests that they came from intact shells, for if the valves had 
lain on the ground separately, the left valves would have carried the most spat. The 
appearance of the shells showed that they came from “ cluckers” (i.e., oysters which, 
when tapped, sound empty). Two-thirds of the spat on these shells were newly set, 
and the oldest had a spat shell of 900 mu, which brings the date of their first setting 
not earlier than August 25. In harmony with this, our plankton table shows a con- 
siderable number of fry ready to set on the 24th, with subsequent relative absence of 
this size. On this latter date also there was a great increase in younger sae: which 
probably furnished the spat that set September 2 to 5. 
On September 18, Hubert P. McNeill took up and forwarded a string of tarred 
shells which we had placed on his beds on August 24, and also a large shell, which 
he wrote was planted August 30. These samples proved highly interesting. Consider- 
ing first the August 30 shell, this was a large left valve and remarkably clean after 
having been in the water for ‘eighteen days.” It carried a small shell on its back 
with its smooth or inside surface facing in the same direction as the outside of the 
main shell, and occupying a seventh of its surface. The smooth inside of the large 
shell carried thirty-four spat, the outside eighty-nine spat, and the small shell thirty- 
eight. Had the small shell been absent, there should have been a hundred spat, or three 
times as many as on the inside; but if the entire surface had been as good as that of 
the little shell, there would have been 266 spat, or nearly eight times as many as on the 
inside. To account for this, we believe the shell hung with the curved side down. 
Had it rested on the ground, the spat would have been excluded from the center part 
of the convex surface. The sizes of the spat shells, viz., 40 to 560 mu, show that 
spatting had occurred within five or six days, so that there is a question as to its 
having been exposed for a longer period than a week. Turning now to consider the 
sizes of the spat shell-growth on the shells placed August 24, we have ranges of 0 -to 
2600 mu. As these shells were exposed twenty-five days, we have another fine 
coincidence on the basis of 100 mu growth per day, assuming that setting began at 
once, which is probable, as the water at the place where the shells were hung had the 
finest show of fry, ready to set, seen in the entire bay. Granting this assumption, then 
there was spatting at this point on August 24, 28 and on Sepetmber 3, 5, 7, 8, 11, 16, 
and 18, with climaxes on the 5th and 15th. The latter climax fits the facts of the 
large shell lifted September 18, but leaves a mystery about the absence of fry on 
September 3 to 5, if it was placed August 30, for the tarred shells corroborate the 
evidence of the McNutt shells. It must be carefully noted, that in all this caleulation 
