PROGRESS IN BIOLOGICAL INQUIRIES, 1938 79 
development and reproduction in hydroids; Russell A. Huggins and 
Sara E. Huggins, Western Reserve University, the scale size of fish 
in relation to body size; Gordon H. Tucker, University of North 
Carolina, gonad development in ascidians; J. Albert Fincher, Uni- 
versity of North Carolina, spermatogenesis in sponges; Stephen W. 
Gray, University of Illinois, physiology of the invertebrate heart; 
H. J. Lewis and Hervey Lewis, Narragansett Bay Oyster Co., spawn- 
ing and larval development of oysters. 
Propagation of the diamond-back terrapin—A record hatch of 
13,600 young diamond-back terrapins was obtained during the past 
summer at the United States Fisheries Biological Station at Beau- 
fort, N. C., which operates the world’s largest hatchery for the prop- 
agation of these salt-marsh turtles. The greatest annual production 
prior to this time was that obtained in 1935, when a brood of 13,245 
was produced in the 5 concrete breeding pens surrounding the sta- 
tion. Artificial propagation of terrapin was first undertaken here in 
1909, and since then has yielded over 128,000 young diamond-backs 
for restocking the coastal salt marshes of North Carolina and other 
Southern States. The 1938 brood has been placed in special hiber- 
nating boxes in the large rearing house and next spring will be dis- 
tributed throughout the South Atlantic region in cooperation with 
the various State conservation departments. 
This year’s high production is attributed to improvements that 
were made in breeding pen arrangements as a result of experi- 
mental studies conducted under the direction of Dr. Prytherch and 
Capt. Charles Hatsel. Since these studies indicated that production 
of young might be considerably increased by allowing the brood 
stock greater room for feeding, egg laying, ete., two large pens were 
constructed to relieve the crowding of adult terrapin in the other 
five enclosures. In the new pens, in which the brood stock was 
allowed approximately twice as much space as during the previous 
year, the production of young by each group (consisting of 400 
females and 100 males) increased from 1,200 and 2,480, respectively, 
in 1937 to 3.360 and 3,616 in 1938. In two other experiments, in 
which the number of adult terrapin per pen was reduced 50 percent, 
there were increases of 25 and 40 percent in production of young in 
1938. In the various experimental pens in which crowding was 
reduced, the average production of young per female terrapin showed 
increases of 3.0 to 5.2; 3.0 to 8.41; 6.2 to 8.4; and 8.0 to 10.1, as 
compared with the previous year. A most encouraging aspect of 
these improvements in terrapin propagation is that general condi- 
tions in 1938 were apparently less favorable for breeding than usual, 
as two of the “control” pens that were not changed in any respect 
showed decreases in egg production of 20 and 50 percent. 
The total brood stock at present consists of 570 males and 2,025 
females, most of which have been in captivity for periods ranging 
from 10 to 25 years. Last season 320 wild terrapin were added to 
this stock and are being kept under observation in a separate pen 
to determine the length of time required to reach satisfactory egg 
production. During the first summer these terrapin produced only a 
few young but showed an increased output of 460 for 1938. In 
experiments conducted in cooperation with Dr. Bert Cunningham, 
of Duke University, several hundred eggs were successfully incubated 
under artificial laboratory conditions by keeping them in holders of 
