54 COMMISSION OF CONSERVATION 



while there were plenty of small silver-shells and Crepidulas, there were 

 very few really small oysters, and they rarely smaller than a thumb-nail. 

 I examined rocks, stones, shells, the lower logs of wharves, rock-weed, 

 eel-grass, gravel, sand, and in fact everything I could think of that might 

 possibly give results, but always without avail. As had been tried during 

 the previous summer, I also used bundles of brush-wood; these were 

 weighted down with stones, or tied and left floating, and were examined 

 with a lens at intervals of a few days. All such attempts were kept up 

 for some time, seemingly without one ray of light, only ever thickening 

 mystery. The long distances traversed to and from the most favourable 

 spots, the faunistic work along shores, by dredging, and with the plankton 

 net, examination of all material collected, perusal of literature, &c, ab- 

 sorbed time, and it looked as if that season would pass with as little result 

 as the preceding. Could it be that our northern oyster was a different 

 species, with some variation in its habits from the southern one? 



Use of Glass Strips as Cultch. — About this time a copy of Jackson's 

 work (Phylogeny of the Pelecypoda, 1890) recalled a method of using 

 glass to catch free-swimming larvse of many adult fixed forms of animals 

 — a method first employed by Mobius. I had become acquainted with 

 this method some years before while working on the clam at St. Andrews, 

 but had forgotten about it until a reference brought it to mind. This was 

 the time to try it. Mobius had used microscopic slides. I judged that 

 for my purpose larger pieces would be of advantage in that they would be 

 more easily handled, not so likely to get lost, and would offer a greater 

 surface. I had window glass cut into strips 2x6 inches and stood on end 

 in crocks — each crock accommodating about a dozen pieces, that were 

 kept from falling together by a coarse mesh-work of wire. These batteries 

 were then planted at various places on or in proximity to oyster-beds — 

 especially just below low-water mark off Curtain island and off Ram Island 

 point. The crocks were partly sunk in the gravel or sand of the bottom 

 and made secure against the buoyant force of the water at high tide and 

 the lateral action of currents, waves, and winds at low tide, by building 

 little pens of stones around them but leaving the tops well open. It was 

 thought that larva;, either swimming about or swept about by the water, 

 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 is a most favourable place, since it has a rocky, 

 stony, gravelly or sandy bottom, with an adundance of small-sized oysters 

 so thickly set that in places it is impossible to step without treading on 

 them. The tidal current coming from the upper bay (towards Summer- 

 side) passes along both sides of Curtain island and, joining with that from 

 Malpeque on the one side and from Grand river and Bideford on the other, 

 sweeps over or past this submerged point on its way to the narrow mouth 

 of Richmond bay, carrying water (and presumably larva 1 ) from almost all 



