DIAMOND-BACK TERRAPIN CULTURE 
51 
In general, those animals that were nearest the stove where the temperature 
was the highest and probably somewhat more uniform than elsewhere made the 
greatest growth. On the other hand, those held in certain tanks rather far removed 
from the stove and placed in such a position that the animals received no direct 
sunshine invariably made the least growth. 
Various methods of sanitation (some of which are described in the section of 
this report dealing with the records of survival) have been employed, but apparently 
without appreciable effects upon the rate of growth. 
One metal (galvanized iron) tank has been used for several years. The animals 
in this tank, which was always placed near the stove, gained a fair to a good rate 
Figure 8.— Rate of growth of two lots of terrapins of the brood of 1917. Line Crepresents the lot 
under close “range” and line W the lot under a wild “range” 
of growth during certain years, and again the gain was quite small. The average 
rate of growth of the animals held in this tank during the period 1920 to 1926, com- 
pared with that of animals held in adjoining tanks during the same period of time, 
is just about equal; that is, the average size of 1,018 animals held in the metal tank 
during the period indicated was 32.5 millimeters, whereas it was 32.3 millimeters 
for 1,195 animals held in a wooden tank placed at one side of it, and 32.9 millimeters 
for 973 animals in another wooden tank on the opposite side. The metal tank, as 
indicated elsewhere, did not bring a lower death rate, for in this respect the results 
also are intermediate of those for the adjoining tanks. A metal tank is kept clean 
somewhat more easily, and this apparently is the only advantage it has over a 
wooden one. On the other hand, galvanized iron corrodes in a comparatively brief 
