REPORT OF COMMISSIONERS OF INLAND FISHERIES. 57 



were found to have more than doubled their length, and in some 

 instances to have trebled it. 



Experiment No. 4. On July 22, 1899, a number of clams from 

 the same shore were planted separately in land tiles set perpendicu- 

 larly in the ground, and arranged in rows, from extreme low- water 

 mark to high water mark, at intervals of about two feet. A part of 

 those in one row were measured again about two months later, on 

 September 18th; they showed a decided difference in the rate of 

 growth, those planted at low tide having grown very much more 

 rapidly than those higher up. In the lowest tiles (except the first, 

 which was empty) they measured respectively 48, 46, and 44mm. 

 (1|, li%6, l^Vie inches) in length — nearly two inches for clams 

 about three months old. 



The more rapid growth of clams lying near low-water mark as 

 compared with those higher up on the shore, so well illustrated here, 

 has often been observed in other instances, and is evidently due to 

 the fact that those at low water have a much longer time each day 

 in which to feed. 



Experiment No. 5. On August 14, 1900, about 1,300 small clams 

 were taken from an artificial spat collector and transplanted in sand 

 boxes suspended about one foot beneath the smiace of the water at 

 the houseboat. About the first of October they were transferred 

 to new boxes on the shore, where they have remained since that time. 

 At the houseboat they grew remarkably fast, but since they have 

 been on the shore the growth has not been above the average. On 

 August 14, the date of transferring to the houseboat, th'ey averaged 

 about 12mm. (^ an inch) in length and, on September 20, they had 

 grown to three times this length and averaged 36mm. (1^ inches). 



This case furnished a beautiful example of the extreme variations 

 in growth, inasmuch as the clams which were left in the spat collec- 

 tor were also measured on September 30 and had increased by only 

 half their length, that is 5mm. (% of an inch). Compare Figure 

 No. 3, Plate No. 2, report for 1900. 



At the end of the first year the transplanted specimens averaged 



