INVESTIGATION OF OYSTER SPAWNING, ETC., MILFORD, CONN. 



475 



fluence. Samples of the oysters always were examined before and after the tests so as 

 to determine the approximate amount of spawn retained or released. In these exam- 

 inations several transverse sections were cut through the body of the oyster so that 

 the thickness of the reproductive tissue could be seen easily. In comparing these 

 sections from year to year a very noticeable difl'erence was found in the quantity of 

 spawn in oysters taken from the same bed each season. In the sections cut anterior 

 to the heart the layer of reproductive tissue surrounding the liver was found to vary 



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S /922 1925 /924 I5Z5 1928 1927 



Figure 28.— Total air temperature departures from normal at New Haven, Conn., for tlio 

 period April 1 to August 1 



t from over 1.5 centimeter in 1925 to 0.5 centimeter and less in 1926 and 1927. A 

 noticeable difference was also found in the consistency of this layer, which in 1925 

 was extremely soft and milky, while just the opposite condition was found the other 

 two years. 



In order to determine the cause of this annual difference in the quantity and 

 ripeness of the spawn as observed on July I, water and air temperatures were exam- 

 ined during the preceding spring months. By using the departure of air temperature 

 from normal as a basis and estimating the approximate water temperatures at 2° 

 below the temperature of the air, we find that for the period April to July 1 the water 

 temperature in 1925 was several degrees above normal, while in 1926 and 1927 it was 

 decidedly below. This is illustrated by Figures 8 and 28, which show the monthly 

 20701—29 4 



