80 U. 8. BUREAU OF FISHERIES 
moist filter paper instead of in a layer of sand, as in nature. This 
new technique will be valuable in future experiments to determine 
the relative importance of various environmental factors such as 
temperature, humidity, oxygen supply, etc., on the rate of incubation 
and survival of young of the diamond-back terrapin. 
Utilization of salt-marsh ponds for propagation of fish and shell- 
fish —Investigations have been undertaken tc determine the possibil- 
ity of using improved marsh areas in the South Atlantic coastal 
region for breeding and growing mullet, oysters, and other marine 
species of commercial importance. In cooperation with the Works 
Progress Administration the construction of a large tidal pond, 21% 
acres in extent, for experimental rearing of mullet was completed 
by the fall of 1938. This was stocked with over 3,000 fish ranging 
in size from roe mullet, weighing over 5 pounds, to immature fish 
having a length of 6 to 8 inches and which are approximately 1 
year old. Less than 1 percent of the fish died from injuries sustained 
during collection and transportation to the pond by live car. The 
tidal circulation renews over half the water in the pond every 12 
hours and apparently has maintained, during the first 8 months of 
operation, satisfactory conditions for breeding and feeding of the 
mullet. This is indicated by the discovery of thousands of very 
young mullet in the pond during the latter part of December which 
had attained lengths ranging from one-half to three-fourths of an 
inch. Representative samples of these small mullet are being col- 
lected at intervals of 1 month in order to obtain a record of their 
rate of growth in this experimental] area. Observations are also 
being made of the growth of the large mullet and the time required 
for the various age groups or schools to reach marketable size, The 
experiments thus far have shown that tidal ponds of this type can 
also be used for the temporary storage of comparatively large 
quantities of live fish until conditions for marketing are most suitable. 
Construction operations were continued on marshland adjacent to 
the mullet-rearing pond to provide shaliow canals and small ponds 
for experiments in oyster culture. These were planted in the early 
fall with several hundred bushels of seed oysters gathered from nearby 
beds where overcrowding produces an inferior quality of oyster. In 
the artificial ponds the oysters have shown rapid growth during the 
first 3 months, October through December, but the real test as to the 
practical value of this procedure will come during the summer of 
1939, when arrangements will be put into effect to protect these plant- 
ings from attachment of spawn and subsequent crowding. Detailed 
observations of the rate of growth of the seed oysters in weight, vol- 
ume, etc., are being made by the use of cement panels to which repre- 
sentative groups of oysters have been fastened, in order that individual 
measurements may be obtained at regular intervals. Different con- 
ditions are being maintained and studied in the various ponds with 
respect to temperature, depth, and circulation of water in relation to 
the density of oyster plantings and time required for the seed to reach 
marketable size. 
APPROPRIATIONS 
The funds for the work of the Division of Scientific Inquiry in the 
calendar year 1938 were approximately the same as for 1937 insofar 
as the basic appropriation is concerned. The lifting of the require- 
