PROGRESS IN BIOLOGICAL INQUIRIES, 19 3 2 145 



In connection with the Fort Worth propagation experiment, feed- 

 ing and food requirement experiments are being carried on continu- 

 ously in the Columbia (Mo.) laboratories. One set of experiments 

 recently completed has shown that fresh-water mussels can live for 

 a period of 18 months or longer without food, but that during star- 

 vation periods serious changes in shell and soft parts take place. 

 Through the studies of the utiUzation of various food constituents 

 by the mussels, data have already been collected showing that the 

 mussels may be fed various inexpensive foods successfully and their 

 health and activity greatly improved. At present a series of tests 

 are going forward dealing with the requirements for shell production, 

 and it has been found that a certain diet greatly increases the growth 

 of shell and the deposit of lime in the shell. These experiments have, 

 of course, immediate practical value in accounting for differences in 

 shell quality in different streams and are to be applied this spring to 

 the feeding of mussels in captivity in the Fort Worth raceways. 



In connection with the artificial propagation work, the factors reg- 

 ulating the spawning and production of glochidia in the gravid female 

 are in progress. One of the difficulties in handling gravid mussels of 

 certain species is a tendency to abort the unripe glochidia. Factors 

 surrounding these complexes are now under investigation. * 



Mussels population and growth studies in various of the major 

 shell-producing tributaries of the Mississippi have been completed 

 during the current year and the data are being tabulated and plotted 

 as rapidly as possible. Over 12,000 shells have been examined; and 

 the relation between chemical composition of the water pollution 

 and erosion silt have been correlated with 'the population, growth, 

 and pollution studies. From these studies it is now well established 

 that, with the exception of the paper shells and certain other unde- 

 sirable species of mussels, the great majority of our fresh-water mus- 

 sels are not maintaining a replacement population; that is, the various 

 commercial species of mussels are falling behind in annual replace- 

 ment even in the undisturbed and closed streams as a result of the 

 increasing pollution and erosion hazards. In the main, there has 

 been little successful replacement of fresh-water mussels in the Mis- 

 sissippi Valley, except in a few restricted local areas, since production 

 of the year class of 1925. 



In connection with all of the mussel studies various observations 

 on the life history, biology, and ecology of various mussel species have 

 been made. One in particular may be mentioned, namely, the very 

 curious spawning of the Arkansas fan shell Cyprogena alberti (Conrad) 

 which has been worked out in the laboratory for the first time. 



INDEPENDENT ACTIVITIES OF FISHERY BIOLOGICAL 

 LABORATORIES 



WOODS HOLE, MASS. 



The biological station at Woods Hole continued to serve the needs 

 of Bureau investigators during the spring and summer of 1932, though 

 lack of funds prevented the furnishing of facilities to guest investiga- 

 tors as had been, up to this time, the long-established poUcy of the 

 bureau. 



Among the activities at the laboratory were: Studies on the physi- 

 ology of the oyster and control of starfish by Dr. P. S. Galtsoff and 



