PROGRESS IN BIOLOGICAL INQUIRIES, 19 2 7 233 



port station, and the work progressed to the point where dozens, 

 hundreds, and finally thousands of mussels were reared artificially to 

 the juvenile stage. During the coming year it is purposed to cultivate 

 mussels on a much larger scale, and it is expected that eventually 

 artificial propagation will reach such magnitude as to make it of 

 importance in rehabilitating formerly productive mussel grounds. 

 The control of mussel propagation will place the production of 

 mussels on a farming basis, where selective breeding, choice of pro- 

 ducing grounds, crop management, and economic marketing will play 

 their parts in stabilizing the industry and insuring an abundance of 

 raw material. 



The second line of investigation deals with the study of produc- 

 tion in various areas by methods for determining precisely the age 

 of mussels, T. K. Chamberlain, director of the Fairport (Iowa) 

 fisheries biological station, has applied the methods developed by 

 Dr. F. W. Weymouth, of Stanford University, to the study of rates 

 of growth of mollusl^ and has been able to determine accurately 

 the age of mussel shells of several important commercial species. 

 Mr. Chamberlain is extending his studies to other localities, in order 

 to determine the condition and composition of the stock of mussels 

 in any given locality and to discover those localities in which the 

 greatest growth is made. The results of such studies will be of value 

 in planting juvenile mussels produced by the new method of culture. 



Mr. Chamberlain continued a 3ystem of mussel surveys initiated 

 several years ago, completing during the summer a survey of mussel 

 resources of Lake Pepin, a widened portion of the Mississippi River 

 between Wisconsin and Minnesota, which, for its area, has been un- 

 usually productive and for that reason has long been the object of 

 special study by the bureau. These investigations are well received 

 by the button manufacturers, who are beginning to feel the scarcity 

 of the more suitable varieties of mussel shells. 



TERRAPINS 



In 1924 the Fisheries Commission Board of North Carolina began 

 to cooperate with the bureau in its work on diamond-back terrapin 

 culture. A larger brood stock was secured, and each year a larger 

 number of terrapins is hatched. It is hoped in this way to rehabili- 

 tate the supply of terrapins in the marghes of the State, The prac- 

 tice of former years of liberating young animals not desired at the 

 station for experimental purposes when they have attained a length 

 of about 2 inches has been continued. 



In 1926, 3,889 animals were hatched at the station. The number 

 hatched in 1927 to January 10, 1928, was 6,319. This number may- 

 be increased by several hundred, perhaps, next spring, when addi- 

 tional young may be found in the egg Ijeds. During 1927, 2,437 

 young terrapins that had attained a length of about 2 inches were 

 liberated. 



An exceptionally heavy mortality occurred among the young ani- 

 mals during the summer of 1927, due to cancerous sores. It is be- 

 lieved that the disease was caused by using improper tanks, and 

 steps have been taken to avoid a recurrence. 



