PROGRESS IN BIOLOGICAL INQUIRIES, 1923. 15 



adjustments, nutritive relations, etc.; (2) the morphological study 

 of the glochidia of a large number of fresh-water mussels; (3) the 

 nutrition of the encysted glochidium; and (4) the histological 

 changes in tissues of tlie host due to an immunity reaction of the fish 

 to inoculation with glochidia. 



Dr. E. P. Churchill, jr., during the summer of 1922 was engaged in 

 a continuation of his study of the food and feeding of fresh-water 

 mussels. His attention was confined chiefly to feeding reactions and 

 requirements of juvenile mussels. 



Activities looking toward adequate protection for the commercial 

 mussels in order that the industry might be perpetuated have been 

 of a cooperative and advisory character. During the year, as a result 

 of endeavors along this line, the fish and game authorities of the 

 States of Minnesota, Iowa, Wisconsin, and Illinois have cooperated 

 to close to commercial fishing for a period of five years alternate sec- 

 tions of the Mississippi River between Brownsville, Minn., and 

 Keokuk, Iowa. 



TERRAPIN. 



A series of cultural and breeding experiments with the diamond- 

 back terrapin was continued at Beaufort, N. C, by Charles 

 Hatsel, the acting director of the station. Careful records were 

 kept of the reactions obtained by varying methods of feeding, size 

 of range, etc., and special experiments in selective breeding were 

 begun. Further attention has been given to the determination of the 

 cause or causes of a bacterial disease among young winter-fed ter- 

 rapin and to methods of combating the disease. 



Terrapin from a wild brood stock have been grown in confine- 

 ment under various conditions for the purpose of determining the 

 environment under which the best results may be obtained. It has 

 been found that at least one year's growth can be gained by placing 

 young terrapin in a hothouse, keeping them warm, and feeding them 

 regularly for the first winter of their lives. Winter feeding for 

 older terrapin has not proved to be of much value. The young that 

 received this winter treatmenf the first year have also invariably 

 reached sexual maturity and produced eggs one year earlier than 

 those of the same age that were permitted to hibernate. Diseases 

 among the winter-fed stock, however, are more prevalent than they 

 are among the hibernating terrapins and constitute a problem that 

 requires further study. Several experiments have been conducted 

 in the past and others are now under way looking toward the suc- 

 cessful control of these diseases. Fortunately, diseases among ter- 

 rapin of one or more jears of age are very rare. 



The oli'spring of wild stock have been reared to sexual maturity 

 in captivity in four years. Several lots of young, hatched from 

 eggs !^id by terrapins reared in the pounds at the Beaufort station, 

 are now being held, and their rate of growth is compared from time 

 to time with that of terrapins of the same age hatched from eggs 

 of the wild brood stock. To date the rate of growth in the oifspring 

 of the '' domestic " stock invariably has exceeded that of the " wild " 

 stock, indicating that as early as the second generation after confine- 

 ment these animals are becoming adapted to the changed environ- 



