9< s BULLETIN OF THE BUREAU OF FISHERIES. 



increase of 346 eggs to be fertilized. The 191 1 winter-fed brood in its fifth year of 

 laying also showed a decreased fertility of approximately 9 per cent, with an increase 

 of 301 in number of eggs to be fertilized. Even with a smaller number of eggs by 362 

 to fertilize in its sixth laying year there was only a 4.2 per cent increased fertility, 12 

 males being present throughout the observations. 



To be compared with these records there are the 1910 selected brood and the 1912 

 winter-fed brood. These contained, respectively, 32 and 24 males per 100 females. 

 The lot with 32 males per 100 females has yielded better than 90 per cent fertility now 

 for the past four years, even though the egg production with the exception of the last 

 year has increased yearly during this period. This is an especially good record in view 

 of the fact that the egg rate in this lot in 1919 averaged 27.1 per female. The 

 1912 winter-fed brood, with 24 males per 100 females, has laid but twice, and it is 

 needless to say the record of these first two years may not be indicative of the future 

 record of this group. However, the egg production was very large for the first laying 

 year, and the percentage of fertility of the eggs in this case may be of considerable 

 comparative value. This record is the highest of our observations for percentage of 

 fertility in the first year where there has been substantial egg production. It will be 

 noted, however, that with an increase of egg production in the second year the per- 

 centage of fertility declined to 85. 1 per cent. 



The 1909 brood, in which there are half as many males as females, has given during 

 the past three years a high record. There is no doubt that there are more than enough 

 males in this lot, since the 1910 select brood has a record equally as good in percentage 

 of fertility and contains only 32 males per 100 females. 



From our table and this discussion it seems warranted to conclude that after the 

 brood has established a substantial egg-laying record a 90 per cent fertility may be 

 obtained with from 24 to 32 males per 100 females. The record of the 191 1 hibernated 

 brood is good with only 12 males per 100 females. This record may be influenced, 

 however, by the fact that appreciable egg laying in this brood was relatively late, 

 coining in the ninth year, and thus much more time for copulation was available with 

 but very slight utilization of the spermatozoa. 



GROWTH. 



Many data at hand concerning feeding and growth and their bearing on the develop- 

 ment and functioning of the sexual organs of the terrapin are of value to the commercial 

 terrapin culturist. The several annual broods, the offspring of the original and second 

 lots of breeders, have had chosen from them certain numbers of individuals which have 

 received varying treatments, the results of which can be compared to advantage. 



The effect of hibernation on the growth of the small, newly hatched terrapin is con- 

 siderably different from that of winter feeding in a warmed nursery house. Whereas 

 the hibernated terrapin grows none during the winter, the fed terrapins may make 

 considerable growth. The food used and the temperature at which the terrapins are 

 kept appear to be the factors most influencing growth in the nursery house. The heat- 

 ing plant employed at Beaufort is merely a large coal-burning sheet-iron stove. The 

 radiation from this stove causes the water of those boxes closest to the stove to remain 

 at high temperature throughout the day and night, while those farther away are not so 

 thoroughly and continually kept at as high a temperature. These feeding boxes closest 

 to the stove alwavs contain the largest terrapins in the spring, while those at the greatest 



