38 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 
or a great loss will result. An additional fact in favor of trans- 
planting at this time is that in some localities there are very great 
quantities of young clams set early in July which, if not taken up 
and transplanted, are destroyed by shifting sand or from some 
other cause. In other localities the clams are set too thick to grow 
to the best advantage, and they would actually be benefited by 
being: thinned out. 
(8) It seems almost certain that the explanation of the abun- 
dant set in a limited area, and the meagre set in the neighboring 
localities, is to be sought in the position of the shore with refer- 
ence to the tides. When this explanation has been worked out in 
detail it may be possible artificially to construct and place appar- 
atus to collect the set in equally large quantities. 
(9) The experiments of transplanting have demonstrated that 
under favorable conditions the rate of growth is more rapid than 
is usually supposed, some of this year’s set having reached a 
length of nearly two inches by the middle of September. The ex- 
periments demonstrate also, the fact that there are great differences 
in the rate of growth according to the food supply which is ob- 
tained from the water, and that the most rapid growth may be 
expected of clams which are under water most of the time. 
(10) The size and age at which the clams reach sexual matur- 
ity has not been definitely ascertained, but there are facts which 
indicate strongly that they breed during the first year of their 
life. It has elsewhere been stated that they do not breed until 
the third year. The question is important, of course, in view of 
any attempt at clam culture on a large scale.or at restocking the 
shores. 
EXPLANATION OF FIGURES, 
1. Sketches, drawn with camera lucida, of young, free-swim- 
ming clams, showing shape and variation in size. 
2. Camera drawing made on June 14 of a clam caught in the 
skim-net at the surface of the water on May 29, and kept isola- 
