66 CONFERENCE OF GOVERNORS. 



size are smothered by falling into mud and slimy substances. Still 

 more countless millions are eaten by elders of their own kind, by 

 young fishes and by tube-dwelling worms. Notwithstanding the 

 utterly incomprehensible magnitude of such infant mortality, the 

 " set " of oysters or clams is frequently so abundant in favorable 

 localities that a struggle for existence begins which does not ter- 

 minate until the population of perhaps 2,000 to the square foot 

 of surface is reduced to 10 or 20. 



It is at such a point that man can render efficient aid to nature, 

 and by transplanting to unoccupied areas turn nature's wasteful 

 prodigality to economic gain. If taken at the most favorable time, 

 say when the young clams are about % inch long, these may 

 be rapidly and cheaply collected by means of shovels and sieves, 

 and sown broadcast over suitable tidal flats, after the manner of 

 sowing grass seed. The size of seed moUusks to be used and 

 methods of planting must be determined for each special locality, 

 and adapted to the physical conditions of current and consistency 

 of the bottom. The number to be grown per square foot depends 

 largely upon the quantity of food available. 



Manner of Feeding. 

 All the edible mollusks, from their anatomical structure, act as 

 living filters, straining out and retaining as food great quantities 

 of microscopic plants (diatoms, algge, bacteria) and minute frag- 

 ments of organic debris, which occur floating in the water. Owing 

 to the fact that rivers bring naturally to the ocean great quantities 

 of soluble plant food washed from the land, the largest quantities 

 of shellfish are found naturally in the great bays and estuaries along 

 the coast, — Chesapeake Bay, Narragansett Bay, Mt. Hope Bay, 

 Buzzards Bay, Boston harbor, the flats at the mouth of the Merri- 

 mac Eiver, etc. 



Effects op Pollution. 

 It must be constantly borne in mind that these useful mollusks 

 are found at the mouths of rivers, because they there find as their 

 food in the brackish water the microscopic plants which in turn 

 are nourished by the soluble nitrates washed from the soil of the 

 uplands. Unfortunately, with increasing population of the land 

 organic debris may enter the water in excessive quantities, and 

 reach the mollusks too directly and without the preparation re- 

 quired under natural conditions. Organic debris is changed into 

 plant food by natural processes very rapidly on land, becoming 



